yeah I'd also like to know more about this - I've searched the forums but it's really hard to get anything of an overview what methods there are available.

Basically I want to have two-way sync of calendar and address book data. Bookmarks would be nice, too..
What options are there? Not limiting it to Thunderbird for that matter but generally, what technologies are supported?
Does IMAP actually work both ways? And is it possible to subscribe to several agendas? afaik there's no caldav support..? no webdav in general? what about ical?