After looking up the price of a stamp (not as easy as it sounds...)
and finding many outdated Q.&A.s,
I finally found the "official" link to the cost
of mailing a "less than one ounce first class" letter in the U.S.
(you know, the typical stamp...)
Here is the link to the United States Postal Service
where you can find the up-to-date prices for first class mail:
As of today, September 8, 2008, the cost for a letter is 42 cents and postcard 27 cents.
(I can't remember when they changed, middle of May, I think. We obviously don't send too many letters!! Sorry USPS!)
I have some stamps to upgrade!! ;-)