All bets are off when it comes to rebates this year. Canon really haven't followed their normal pattern. I'd guess this is a cumulative effect involving production problems following the Tsunami earlier this year, the worldwide economic slump and the strength of the Yen vs. the dollar. In early 2010 the Japanese camera makers were getting 91 Yen for every dollar. Today they are getting 77 Yen for every dollar. So they are making about 15% less just due to the shift in exchange rates.
We haven't seen any new Canon products recently either. Typically a new DSLR has been announced in mid-late August. Not this year. I guess there is still time. The rumor mill is always strong, but mostly to attract eyballs to the rumor sites to generate advertising revenue. I'm sure Canon have a bunch of new prototypes in the works, but when we will see them, nobody really knows.
So I don't see any heavy discounting of the 5D MkII anytime soon. I'd be very surprised to see a 5D MkII + 24-105 combination for $2500. The 5D deals were several years ago and prices have been going up, not down. Right now the 5D MkII runs around
$2499 and the 24-105 runs around
$1065 and I just don't see a $1000 discount on the pair as being very likely. Even $500 seems unlikely. I could see maybe $250 or so, but I've no idea if any such rebate is being planned this year.
Of course sooner or later there will be a 5D MkIII, and that will drive down the price of the 5D MkII somewhat - but at that point you'll probably want the MkIII anyway.