This time they were able to do it via a straight vote. 151 to 45. 50 votes actually would have been enough to get the referendum, but even if nobody abstained they weren't quite there. Apparently the next election opponents can try for is 2012. Since people get more comfortable with gay marriage as they have more experience with it, I think we can call this one a lock.
On a similar note, if anyone knows a effective advocacy group for gay marriage in Maryland, lemme know and I'll give them some money. I'll get around to just finding one at some point, but I've been busy, albeit with vacations, of late.