He's getting a lot of screen time. I learned about him first on Life with Arie. He's also on Philosopher Mouse of the Hedge, and Pippa Dog Blog.
(picture from petition page on change.org)
Sgt. Rex's story is one of the exact reasons I support the Canine Members of the Armed Forces Act. He's a 10 year old German Shepherd who has more than earned his retirement. He has a person, Meagan Leavey, retired marine, who's completed the paper work to adopt him, who loves him and has worked with him, and was injured with him in Iraq. My very own Senator, Charles E. Schumer, has already written a letter to Michael B. Donley, secretary of the Airforce (the Air Force is who trains Military Working Dogs, at Lackland Air Force Base), supporting Sgt. Rex's "rotation to a civilian lifestyle" (my words. I don't know what the letter said).
Edited to add: This is the petition that Senator Charles E. Schumer has on his web site: http://schumer.senate.gov/Contact/sgtrex.cfm . I'd urge signing that one specifically, as the other one (on change.org) might not have as much weight.
Here is the petition, also to be sent to Michael B. Donley, that wants Sgt. Rex to go home with Cpl. Leavey: http://www.change.org/petitions/help-sgt-rex . Please sign it, and share the information. Every dog deserves a home!