iTunes 7, not sure why I upgraded, nothing that exciting apart from the album art fetching feature.
Now I really wish I hadn’t – it crashed on me and I lost my entire library, got that back from a backup (once bitten, twice shy). Now it starts up, spends about 1 hour doing the gapless playback analysis bollocks again then crashes in a heap when I shut it down, meaning it goes through gapless shite again on next start and so on, ad infinitum. Don’t bother with version 7, at least 6 worked.

Update – luckily I backed up my iTunes library files prior to the upgrade; I’ve uninstalled 7 put 6.0.4 back on and copied over my backed up DB. It’s all working like a charm.