Rosberg to BMW has been rumoured for a while. It seems as if he'd replace Heidfeld although Kubica could leave as well if he gets a big money/team offer (Brawn?). Nick's not been driving badly but neither has he been outstanding over the last 3 1/2 seasons. He'll get another drive somewhere, probably one of the new teams
Barrichello to Williams first came up
here courtesy of Mr J Allen, as well as the Rosberg/BMW move and Buemi's potential future move to Ferrari
Sutil to McLaren would be another potential move, I think