I was on www.twlightsaga.com and in one of the groups "Robert Pattinson Fan Club" someone posted that thet read in "adult" magazine that Rob and Kristen are getting marred in March, as for right now that's the only pleace I've read about it, don't know what magazine or what country it was from. Sorry.
I find alot of that speculation to be groundless dribble printed to sell something. But considering the timetable of the past two films and the current one in production (Eclipse...release date 6/30/10), it could very well be true. ;-) It could be just about March, when Breaking Dawn begins production and Edward and Bella marry. Just my 2 cents.
I could be wrong and frequently are, but I will let you know for sure when I get my invite.