Studio why are you going to buy a D3100? Just buy the new D90 it'll have video too. Or are you going to buy the D3100 and a few weeks later "upgrade" to the new D90?
Nah . . . the D3100 is pretty affordable, and I expect the new D90 to be hundreds more. Unless the new D90 turns out to be significantly faster (more sensitive) than the D3100, it won't be worth the added expense just for filmmaking applications, which is all I'd be using the D3100 for. Also, I really want to move to an FX body to shoot stills, so I gotta reserve some cash for a current-model D700, since a new FX body from Nikon maybe as much as a year away.
Also, I may have just courted my first commercial account, so I think I may really "need" an FX body . . . now! I hope I get it (the account)! It's a bikini company!