Well according to this the breakdown of Avengers on Team Cap vs Team Iron Man are set. Must say I'm surprised, I saw Widow sticking with the rest of S.H.I.E.L.D. on Cap's team, and I didn't include Winter Soldier or Ant Man in my "fan-casting" of this.
I found it interesting that Vision chose side Stark, then I remembered that this Vision is based on JARVIS and will probably be following some kind of protocol, or just siding with "daddy". Both Widow and Hawkeye could fit on either team really, and may be playing double or even triple agent roles. The only real wild card here is Scarlet Witch, and even though she hated Tony for most of her life she could agree with his methods now that they are on the same team.
I'm hoping that Spider-Man has a role much like in the comics, where he switches teams, and ends supporting Cap. Also I like the Black Panther is on a mission of his own, and will remain neutral. It just wouldn't make sense for him to jump right in a fight with people he just met.
Of course this is still rumor, so only time will tell if this is exactly how things break down or not.