It's time to say "good-bye" to some of our favorite stamp sets. After years of dedicated service, the following stamp sets from the Spring-Summer Collection 2008 are retiring. So, let's give them a big sendoff and wish them all the best as they begin a new chapter in their lives. But don't wait too long--they're only available through August 10, 2008, and then they're headed to warmer climes! You can view the list of retiring stamp sets by clicking here.