Hmm. Something Bad has happened :-)
Erming crashed during sync (ISO date format issue, see upthread) and I killed it from the command line.
Now the main N900 calender app denies any knowledge of the calenders I created for sync'ing (only) from Google to, as well as the 'smart' birthdays calender.
Could a lock be wedged somewhere I need to clear ? Rebooting didn't help.

(I have my events backed up to google, so this isn't the end of the world for me)