I would go with the 360. It's dashboard is far more advanced than the PS3 - while sony had more time to match it, even steal ideas and upgrade them. So far the exclusive titles are more apealing on 360 (imo). Even the games that are not exclusive, for instance Call of duty 3, perform better on 360 (surprisingly since on paper PS3 is supposed to be slightly more powerful).
In short, the only reason so far for me to still buy a PS3 would be Metal gear 4, and chances are it will not stay exclusive to PS3 so...
All other aspects (price, game library, online functions, dashboard...) so far are superior on 360.
This is all IMO ofcourse, but know that I am not a sony or microsoft "fanboy" but a gamesfreak in general. On one hand I am hoping sony wont give me a reason to buy a PS3, saves me money, but on the other hand if they DO give me a reason that would mean all the more joy to me.