There is some nastiness available here.  Necrons can not only swap out to a viable six Night Scythe MSU list with the new flyer rules, but Tesla is nastiness incarnate now that the negative for AP- weapons is gone from the vehicle table.  The new hull points rule make Gauss even more lethal to them as well, so the foot and hybrid lists can shine. 

Consider this for Night Scythes: 1.  Their passengers don't take damage when they go down.  2.  They can even drop passengers when in Zoom mode.  This could be fun, but at  S40-50US per model, it can get fairly pricey for the pocketbook.
I'm betting that at NOVA, Necrons will be providing the highest amount of flyer spam.

At least for Black Templars.  Right now I'm going to be doing all my brainstorming on new BT lists over at Marshal Laeroth's.  He has a wider reader base and it is easier than bouncing around the various blogs.  Currently we have several lists up and linked.  Nike has a gunline list linked, Marshal Laeroth has a couple of allied lists (vanilla Marines and Dark Angels) and I've got both a straight Terminator heavy BT list and an allied IG list, which is really an outline.

Found on GW's Facebook page

The TRUTH about the Horus Heresy; The Emperor was actually clearing the final proof of the 3126th ed FAQ, but Horus, irate at the wait for the update to his favourite game, invaded GW HQ to get the documents.

This move was sadly mistaken as an attack on The Emperor's sovereign status and caused the current divide in The Imperium.

The Emperor was sadly put on the golden throne after being hit by a flying model Bloodthirster, thrown by a rage quitting Angron.

Good, Bad & Ugly.  Some of this I need to double check as I've just skimmed a few bits before I get ready to go out.  We really need our FAQ up quick or I'm going to have to jump ship.

Bikers appear to use their modified T vs ID, which is cool, but not just for us.  In the Appendix of stat lines, our "elite" Sword Brethren are nothing more than plain jane Initiates still and not in line with anyone other SM codex's "veterans" that are their "elite".  EC just dropped to S4 and does not pick up the extra A that should have been there.

Allies definitely cannot share rides, but the idea of using a Straken list to bolster Templars still has some merit.  Not nearly as much though.  Also, the Black Templars are rather oddly the only Marines that are not "allies of convenience" with Sisters.  I'm actually out to lunch on this entire Idea now regarding allies for a Templar force.  Oh, I could still field a foot IG platoon, but really...

As for the Necrons, no clue without a FAQ, but right now, I'm I'm wondering if any of the elites will get enough love to be viable.

Yes, this is into the "wait and see" mode, but thinking about BT & IG with "Brothers in Arms", the fact that the EC isn't considered a named or special character, instead of BT with IG allies, why not IG with BT allies?

Consider, Straken for BN HQ, at least one platoon of infantry (others might be meltavets or such) then add in the EC, two 12-model Crusader squads (assuming they get frags and better setup) and maybe a Sword Brethren squad (again, assuming GW fixes them).  The idea is that Straken will confer his Furious Charge and Counterattack to our troops, plus the EC will give us "hatred/rage" (+2A in CC, what I'm fairly sure we are getting) while the rest of the IG provides the base of fire for the assault.  Even toys like a Speeder squadron and a Dreadnought could be tacked on.  The key is if the EC becomes a "special character" or not for the purposes of being allies, because if not, then we can benefit from some other codex's named characters by making them the "primary" army.

EDIT:  <sigh>  The rumor around the Net is that you cannot ride in your "brothers in arms" rides, even though you share special rules. 

IG driver: "Lord Champion of the Emperor, hop into my vehicle and I will take you and your men to the <relic/targeting array/shrine/shield generater/other objective> before all is lost!"

EC: "Nay, good Guardsman and loyal servant of the Emperor, this is forbidden to us!  We shall strive our best on our own feet to cover the impossible distance!"

IG driver:  "Milord, you must get in for even your mighty physique, long training and formidable powered armor will not let you cover such a distance in the short time left to us!"

Chaiplain: "Allow me Lord Champion!"  EC nods.

Chaplain: " Brave Guardsman, I know your heart is in the correct place, but you veer dangerously in your beliefs!  It is written in the book of the first High Marshall as handed down by Dorn from the Emperor thusly:  'Thou shalt only ride in the Rhino and Land Raider.  Thou shalt not ride in the Chimera or Repressor.  The Chimera is not for thee, but only the Rhino.  You will be let slide on the Stormraven, though the Thunderhawk is the only proper flying ride.  The Drop Pod is also allowed thee, as well as to thy Dreadnought Brethren.  The Valkyrie and other transports are not for thee, thou shalt not ride in them, on them or even walk too closely to them, they are denied thee.'  Thus the words from our Emperor, Primarch and First High Marshall."

IG driver:  "But my Lord Chaplain, this is to save the Imperium and for the Emperor!"

Chaplain: <pulling his crozius from the Guardsman's skull>  "I am sorry for that, but I have saved this brave warrior from the taint of heresy.  Shall we run brothers?"

So, I'm off to a nearby town to play in a little 400 point skirmish tournament using Adepticon rules.  Yes, this is about 5th Edition, but the theory will fit into 6th, and IMO be a testbed for the new Allies rules.  Especially if, as I fully expect, NOVA 2012 ends up jumping to 6th at what is really the last minute for a 6thish-NOVA-FUBAR Edition tournament.  Anyway, back to the list design.  Only requirement is one Troop and then you can use up to one of any slot, including another Troop.

Hmmm.  Okay, I have plenty of BT, but the rules say nothing greater than AV12 unless a DT, so there go my dreams of a LRC with a squad inside.  How about my Necrons?  At 400 points?!  You must be joking, especially since not only do you need 90 points just to field the Royal Court models that make the army work, but a Necron Overlord is illegal because he has three wounds...  Wait, what about my Witchhunter inducted Guard platoon?  That actually might work...

Rumor this, rumor that, there have been so many rumors around and around that between people claiming to have a "mainline" into GW being cagey, to people who can fake GW well enough to make things up, it is all contradictory.  Rumors of making vehicles weaker, rumors of making vehicles tougher, rumors about new movement rules, shooting rules and assault rules.  With all that, I'll make a prediction you can take to the bank...

GW is totally ignoring the 8000lb gorilla in the room.  After all, this isn't a mere "rules update" or "adjustment", this is supposed to be a whole new edition!  If serious changes need to be made, now is the time to make them!