I've used IM+ for a few years now and like it. The newer versions even talk to Facebook Chat. Works fine on my TP2 (had it on a i760, i730 and i600 previously).
I did have some minor issues at one point with it and not showing all the online contacts... but that was only on the TP2 and haven't really noticed it since. So maybe it was me screwing with registry tweaks that caused the issue.
--chris