That's what I'm like, never bothered with the other stuff but loved The Postal Service. Just looked on their website again it's been updated to show a re-issue of Give Up (with 2 new tracks), an appearance at the show gJ mentioned and "more to come". I hope they do make a new album, but it's been forever and it might end up crap like No Doubt was last year.
edit - just looked on twitter and there's a tweet that reads:
Maybe it'll be like Refused, touring around again.