I updated WordPress to 3.0 the other day and surprisingly, had quite a few problems.  In particular, the LifeStream plugin doesn’t seem to be very happy.  The update process for WordPress itself failed once but succeeded when I ran it again.  I had to actually delete LifeStream and re-add it and even then, it wasn’t quite happy.  The updater never returned but WordPress seems to be operating ok.  This is the first time in 4+ years of using WordPress that I’ve run into anything like this.  Hopefully it will not be a big issue as I have a number of sites I need to update.