Weird thing this morning - I launched iTunes, and got a message saying that a new version of iTunes was available (5.0.2), and would I like to download it? I said yes, and it took me to the iTunes site, which only offers 5.0.1 still.
Dunno what that means, but maybe there's another update imminent? On the other hand, I was still half asleep, so maybe I misread/imagined it.......
Update - it seems I'm not the only one - glad to know I'm not going mad! Thanks go to tufty for the link.