You are correct it is still in service. Although technically the A-10 was scheduled to be retired in 2002. But seeing as the US military still needed a low altitude air to ground vehicle they canceled the retirement and extended the service of the A-10 until 2028. If that holds true the A-10 will see a longer strech of military service then any other warplane in history. 52 years (1976-2028).

In reply to this comment by james_austintx:
"WAS"? It's still in use....

In reply to this comment by gorgonheap:
the A-10 was a freaking sweet piece of military equipment