While Grey Knights and Necrons were also designed for 40k6 they still have some strong ties to 40k5. Horde armies have some inherent advantages for 40k6 and work well behind the safety of the Aegis defense line. From what've I've seen so far there are not a lot of new vehicles being introduced in the new CSM codex other than the new flyer. Sure there are a couple of new walkers but they both have very similar stat lines to the dreadnaught. That in an of itself tells me the emphasis is placed more on infantry.
If we look at Necrons as a counter example that codex introduced many new vehicles in comparison such as the two flyers (Doomscythe and Nightscythe), Doomsday Ark, Ghost Ark, Catacomb command barge and the Annilihation barge. To me that's quite a huge difference and tells us that vehicles can still have a place in certain armies. Transports took some big hits from the nerf bat which I think is good for the game overall since mechanized MSU dominated 40k5.
The meta is still very new for 40k6 and it will probably be at least another year before we start to see any major lasting trends. 40k4 was dominated by infantry heavy armies often featuring gun lines and I can see a return to that style of play... The big difference is the inclusion of flyers which have really shaken up the game since the release of 40k6.
It will be interesting to see if the new Havocs become a steadfast component of CSM armies since they will have access to flakk missiles - probably this will be the case, at least during the beginning. The main topic is horde but probably it would have been better just to say infantry heavy since not all armies have access to horde style units such as Orks and Tyranids.
BeakyCon2 is right around the corner and it will be interesting to see what types of lists are the most competitive. It would seem that the majority of the players are using allies.