The gear in my "fun" rig hasn't changed much for the past six months or so. The only addition has been a Kenwood audio timer (adds convienience, not sonics so I don't really count it much), the only swap was to try out a new wiz-bang Denon Digital tuner with RDS (and that swap might end up being temporary, anyway). So, the pre, the amp, the speakers, and the CDP (no phono in the main system ATM) haven't had any turnover. My "audiophile" system hasn't had a single gear change in over a year. I suppose that both must point to a level of contentment.
That being said, I still pick up some gear and hit the thrifts quite regularily. Having "system nervana" at home does have it's advantages: I pass on many, many pieces that I would have eagerly rushed home to try. I do pick up a little bit of stuff (my wife would probably say a lot), but it's more because I find a piece interesting. I pass on a lot of decent solid-state stuff that I would have grabbed up a year or two ago in favor of vintage tube junkers (console pulls even) that I can play mad scientest with. I guess I always hold out the hope that I'll run across some sale and win the audio lottery or something, but these days it's more about curiosity than upgrading the system.