The main season is June, with events mainly in the UK and some massive rides (but often at night) in the USA.
The event has reached a sort of plateau as far as numbers are concerned. I have been looking at the various Facebook sites and numbers are a little down on last year at this stage, but in the UK at least, we have another 4 new rides proposed.
I think the turn-out for the ride depends as much on the weather as anything! We have been lucky at Brighton in recent years and I am sure a 'heatwave' weekend will increase numbers and a washout one will shrink the numbers by 50%! So it really is a matter of luck......here's hoping 2011 will be a scorcher!
The behavior some of the snappers (not OCC members, I hope) is causing some organisers to re-schedule the starts on some rides, as they tend to put some riders off, before the ride starts. I can see more riders stripping off only at the last minute this year, which will reduce the photo ops, but if you take the plunge and join the ride, you will have a great time and the ladies will usually be happy to pose for a fellow nude rider!