I went to the site but could find no information about it. I have emailed them and will post whatever reply I get here, just for completeness. It would certainly be nice not to have to do all the file deletions/uploads “manually” any more.

unfortunately I don’t understand much of the PHP stuff. Check it out yourself: http://www.zirona.com/software/wordpress-instant-upgrade/

I updated my site to 2.5 yesterday and it went without a hitch. The theme stayed as it should – in fact, I think it looked a bit better, but I may be imagining it! The last upgrade (to 2.3.1 if I remember correctly) was a complete disaster – I lost all my database files and screwed the system. Not good.

Stefan, how does this “instant upgrade” plugin work? My hosting company keeps PHP safe-mode on, and most of these auto-upgrades I’ve tried require it to be off. It might be time to stop being cheap and find a better hosting company :-)