So I subscribe to Game Informer, mostly for the cover stories/exclusives that they get. While the fact that the internet means that GI is essentially useless for news/reviews, they did reveal awesome games first (inFamous, Bulletstorm, etc.), and getting the word on games like Rage/TES:V, and BF3 makes it worth it IMO.  
 
Anyway, on their site they usually have additional content from talking to the devs during their cover story writing process, which is awesome since they get to interview leads at all these games. Anyway, the recently did some for BF3 and talked to their technical and audio designers and well...holy shit.  
(watch them here, pretty sure you don't need a subscription:  http://www.gameinformer.com/b/features/archive/2011/02/28/war-tapes-the-sounds-of-battlefield-3.aspx 
http://www.gameinformer.com/b/features/archive/2011/03/01/the-technology-behind-battlefield-3.aspx     
 
This shit blows me away and really makes me respect those dudes...while in other dev diaries you see sounds from games like CoD or Halo being fakes (I believe it was halo but they basically banged on pots and shit to make metal noises, FO3 did the same), but in the BF3 video, we see that DICE sent dudes out to a Swedish training exercise to get sounds for BF3...tank noises, gun shots, etc. That level of dedication is really impressive and I have no doubt that this will make BF3 sound awesome when it comes out...the guy also talks about how he wants BF3 to sound more realistic than over the top (which they did on previous games).  
 
The Engine stuff, while less impressive, is awesome as well. It's great to see what makes the pre-alpha footage looks so good, and the systems they're incorporating into the game makes it sound even better as well.