So here's the skinny.
As of January 22, 2012, the new rates are as follows:
Source: Postal Service Adjusts Mailing Services Prices for 2012
It is important to note that the U.S. Postal service "Forever" stamps will reflect the current first-class rate. So, if you are using a numbered stamp, or a Zazzle-bought stamp etc and it says 44 cents, you'll need to make sure you add a 1-cent stamp. However, if you're using a Forever stamp, it becomes worth 45 cents so you don't need to add extra postage.
All postage released at first-class rate in 2012 will be Forever, and all of the later releases in 2011 were Forever stamps. As much as I miss the numbers, and combining old/vintage stamps to provide the proper face value, I have to admit that the Forever designation is handy and a good value.
Use up your 98-cent international and your 29-cent postcard stamps while you can!