I'd love us to sign Abidal, but I don't think it'll happen. If he joins it will be permanently rather than a loan deal, and Wenger said a few times that he's not looking for solution beyond this season. Another problem would be registering him with the home grown players rule in place.
Correct me if I'm wrong, but I think we can register only 17 players older than 21 who are haven't trained in England for 3 years before they turned 21. The players registered since the start of the season are: Fabianski, Almunia, Santos, Vermaelen, Koscielny, Mertesacker, Squillaci, Sagna, Arteta, Rosicky, Benayoun, Diaby, Arshavin, Gervinho, Park, RVP, Chamakh. Henry is our 18th non-HG player so by registering him we've unregistered another player (I'm assuming it's Almunia).
So this situation forces us to sell before we buy the likes of Abidal, Podolski etc. and I don't think Wenger will do that. Sadly, the best we can hope for in this window are the likes of Bridge/Richardson on loan :\