It'll be interesting to see if there are any new drivers making their debut this season.
Actually there's is a few new guys this year, as well as some returning rookies who sat out 2011.
Romain Grosjean steps up from gp2 (he was champion) and replaces Petrov for Lotus. Petrov is now without a seat for 2012; Jean-Eric Vergne lines up for Toro Rosso; and Charles Pic for Marussia F1 (formerly Virgin). Interesting that they are all French as there's been a lot of talk about F1 finally returning to France, so I imagine they have significant commercial investment behind them. New guys Esteban Gutiérrez, Giedo van der Garde, and Valteri Bottas have all secured test driver deals with various teams.
Nico Hulkenberg returns to the grid, having replaced Adrian Sutil (who's having some legal issues); Narain Karthikeyan will drive a HRT; and, somewhat sadly - Ruebens Barrichello has lost his seat to Bruno Senna. With 19 consecutive seasons to his name (longer than I've been watching F1) his absence might feel strange to me.
Toro Rosso actually replaced both their drivers rather unceremoniously late in the game, so Daniel Ricciardo (GO AUSSIE!!!) joins Vergne. This leaves both Jaime Alguersuari and Sebastien Buemi without a race seat for 2012, though Buemi did get the test driver role for Red Bull.