Highlights of new rates:
regular letters go up from 41 cents to 42 cents. If you have "forever stamps," you do not need to add the penny.

Priority mail minimum price (14 ounces to 1 pound) goes up from $4.60 to $4.80.
Priority mail flat rate envelope goes up to $4.80 as well.
Prirotiy mail flat rate boxes go up about a buck, to $9.80 (small) and $12.95 (large)

International Priority Mail flat rate envelopes go up 95 cents. Canada & Mexico will be $9.95; other countries across Europe, Asia and elsewhere will be $11.95

International first class: prices are going up, but also the post office is charging 20 cents more to mail a box (package rate) versus a large envelope. Even if they're wrapped in an envelope, "Pieces that are rigid, nonrectangular, or not uniformly thick pay package prices."

For those who use their computers to generate postage/labels, some discounts may apply to the priority mail and express mail rates.

Link to post office's notice of fee changes: http://pe.usps.com/2008_RateCase/Notice123/Notice123.pdf