In Avengers vs. X-Men Program Guide (free at ComiXology), why is the Wolverine depicted fighting in the Avengers side of the brawl instead of X-Men?
First off, this is a great question and not something I've spotted. I think the definitive answer will be given when we get to see the comics. But until then let us have a look at the other promo/teaser work:
Here we see Wolverine Vs Captain America (possibly on Shield HQ)...But, wasn't Wolverine on the Avenger's side? Which side does he pick?
In this last picture it's abundantly clear: Wolverine is caught in the middle of a fight between the two idealogical champions of both sides, Cyclops and Captain America and doesn't have a natural side top pick. The thing is, Wolverine isn't going to be on anyone's side but his. He's a maverick and he'll do what it takes to:
keep Hope, the mutant 'messiah' safe.
He's already been approached by Captain america to take sides and his response was less than definite. He has history (literally) with Captain America, he's worked with Cyclops and he's been involved with the:
Last incarnation of the Phoenix entity's last 'victim' Jean Grey
So he has ample choice of who he sides with, except the last I heard he'd split from the main bulk of the 'X-Men', who now reside on 'Utopia' who are led by Cyclops. The reasons for splitting are ultimately tied up with Wolverine and Cyclop's rivalry.
Here again he is stuck in the middle...
In summary, Wolverine is not explicitly allied to "Cyclops'" side, and may very well change his alliance (to the Avenger's, or his own third side) as the series progresses.
I think Wolverine has a natural occurrence of independence hence I'm the best at what I do. It also happens that Beast is alongside the Avengers because he chooses to go with Wolverine. At the beginning Wolverine understands the force of the Phoenix so he goes with the Avengers but not to do any damage to the X-Men - just to stop them from doing something crazy. Namor rocks!