David Rogers is analyzing the iCal/vCal stuff too but from the perspective of using Palm Desktop like Apple's iCal. The Mac version seems to import/export and merge the vCal format. I just pulled up Palm Desktop v4.01 and it doesn't. I can select one entry, right click and choose "send vCal event" which will open up my Mozilla email with a vCal event attachment, but that's it from what I can see.
Personally, I'm jazzed. It's just like Userland's instant outline stuff - sharing, merging and viewing info via interchange of standard documents on the web. But I'll say again, it's too bad iCal is not XML. It'll be nice when the xCal format catches on (if it does...).