A DPR forum poster dropped in a tidbit of info that he got while shopping for a Canon 5D:
Well, I was a bit sceptical about all the 5d MKII rumours. I stepped into my local camera shop as I was about to buy the current 5D when the salesman said I should rather wait until the 24th of April as the worldwide launch of the new 5D is happening then. (via)
As some astute forum members pointed out, this may be a situation where the salesman is just reading rumors online and pumping them up a bit. See this previous rumor on an April 22nd announcement.
Regardless of the propriety of this recent rumor, stay tuned to the Canon 5D Mark II Rumors page for the latest updates.