I'm using a bunch of computers, so I use imap for my email so my read/unread mail / folders all carry across. I *love* that kmail lets me tag email. How do I get my tags to be attached to my imap email regardless of which computer I'm on? For example, that if I tag an email as"work" on my laptop that it still shows with that tag on my desktop.

Do I need Kolab for this?

I don't think that this is possible even with Kolab. You may be able to get away with syncing the *.index files used by KMail, but this would be prone to corruption if you had either running during a sync.

I think this is planned for 4.5 - but I could be wrong.