I have one, it doesn't cause any problems, but it does serve as an early warning system if my bike fit isn't perfect -- it fills up when my patellar tendinitis flares up. I had it drained when it first appeared - it popped out the back of me knee after one really long ride on a too-high seat. The draining relieved the pressure, but other than that it doesn't really seem to be a problem in and of itself.
Good to hear. I think the issues I'm having with my knees at the moment (including the cysts) are the result of poor bike fit on the bike I bought to stick on my trainer. I've never had any issues whatsoever with my road bike, but I didn't really think too hard about fit on the beater I used with my trainer. D'oh!
Glad to hear that it's manageable. I take it that they never fully go away though, huh?
Mine has been around since 2003, and other than the initial scare - "OMG i have Knee Cancer!" - it has not been an issue. As I sit here today, having barely ridden in the last 2 weeks, it's undetectable, but if I went out and road a hard climbing ride I would probably have a bump there. My doc said it could be surgically fixed, but since it is more a symptom than a problem for me, I haven't felt like anything needed to be done.