I found this mailbox, painted to look like R2-D2 from Star Wars, outside the Museum of Science and Industry in Chicago when I was there last October. The website it refers to, USPSjedimaster.com, seems to have been removed from the internet now, and the promotion dates back to at least March 2007. It seems to have been a contest to determine what Star Wars character would appear on a new stamp - it would seem that Yoda won.
I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide. In case this is not legally possible, I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.