It's a loan till the end of the season, right? Logically it should be till the end of the season.
Many might laugh at Roma for this move, but I think it's a good one and they don't lose anything at all, while they can get something, or even get a lot.
Toni is after all someone who knows calcio well, scored a lot before he left and a target man is exactly what the Romans have been missing. With players like Totti, Vucinic, Menez etc, Roma never had a problem putting the ball in the box, but they had a problem with presence in the box and putting those balls into the net.
It might be an exaggeration, but I see Roma as strong favorites for the 2nd place. Afterall, they are only 3 points behind it now (although Milan has a match less, away to Fiorentina), they started playing better and better, and with a little luck (Totti staying fit) they will make it to 2nd.
Bad news for us though.