I also just read on Stamps.com, that they are USPS approved
Is this real postage?
Yes, PhotoStamps from Stamps.com are valid U.S. Postage, based on a technology called PC Postage, which is what creates the bar code you see to the right of the image area on PhotoStamps. Only vendors that are licensed and approved to produce PC Postage may display the logo seen below:
Stamps.com, the company behind PhotoStamps, has been a USPS-approved provider of PC postage since 1999, and is the industry leader. When the product first launched in 2004, PhotoStamps by Stamps.com was the first customized postage product ever to be offered in the United States. On May 11, 2006, Stamps.com was authorized by the USPS to print business logos, messages and images on PhotoStamps.