On May 14, 2007 there will be rate increases for sending most items via the U.S. Postal Service. You can find lots of good information on their web site here.
In addition would do well to download and print out the special file/document on this rate change.
Most of us will be needing 2 cent stamps to add on to 39 cent stamps used on letters.
Post cared will be 26 cents. Envelopes of standard sizes for letters will be 41, 58, 75 and 92 cents per ounce. There will be an additional fee of 17 cents for oversize envelopes or any that can't be machine fed.
For people sending things by Priority Mail, you'll be needing 55 cent stamps to add to Flat Rate envelopes and $1.05 stamps to add to Flat Rate boxes. The new rates will be $4.60 and $9.15.
I bet there will be long lines at the Post Offices as many people won't be able to figure out the new rates or they won't have the correct add-on stamps. I'm lucky that the PO near me has automated self service 24/7. It's no good for under $1.00 items, but they will have up big signs telling the new rates. Be sure to buy any needed stamps now. Don't wait or they will sell out soon.
I bet that FedEx and UPS will be adding to their rates soon as well.