Sad news: XMarks is shutting down soon, which is a spew, since I found it really handy to sync my bookmarks across several computers and my iPhone.
Fortunately, Firefox Sync will sync my bookmarks (and history) across several computers all using Firefox. And the neato Firefox Home will enable me to access the bookmarks on my iPhone. So I'm happy-ish again.
Still a pity that XMarks is going away, though.