I should think quite a few drivers - Sutil and Glock spring to mind instantly - will have asked their managers to see what options they might have in their existing contracts. It was thought that Renault were talking to Adrian about their second seat last year, though I don't know if that was genuine or just paddock talk.
Both Virgin and Force India used mash ups of last years cars in the first test so will have little idea about how their new cars will run this season. I imagine that Glock will have a good idea that Virgin won't be in any position to challenge on the scale of Renault so I expect he'd jump at the chance. For Sutil I'm not sure if it's such a clear cut choice.