Good question. I haven't seen any news about the next one, yet. Maybe we need to send some mailing list messages and see if someone does? BTW, the rides I have a mind to keep an eye on are as follows:

UBomb
Midnight Mass
Critical Mass
Gallery Stroll Art Ride (this is a tradition that I'd like to continue!)
Sunday Sprints
Alley Cats

Are you familiar with any others? I think I remember hearing that there's also a regular Wednesday ride by the guys in BFC. I'd place these on your wiki, but I'm not in the mood to create an nth account to keep track of this month. Is that a requirement of the site or necessary in your experience to keep vandals from going nuts?