The US Postal Service is having money problems, the worst ever in their history. Stamps are allowed to go up in May 2009 by a maximum of 2 cents. If you are buying stamps in April or May, don't buy too many at the current rate or you'll find yourself back at the post office having to buy a bunch of 1 or 2 cent completer stamps.
They are also considered cutting mail delivery to 5 days a week instead of the current 6 days.
See the attached msn.com news link:
UPDATE 2/15/09 - Told ya so! Stamps are going up 2 cents in May!