HOORAY! Congratulations! I mostly lurk, but I've read about your horrific situation for some time now and am so happy it's finally going to be history! I forget where you live, though. Is D.C. nearby? Do you have to move? Regardless, time to celebrate! Yahoo!
Edit: HAPPY. I'm happy it'll be history. I'm sorry it has been a huge PITA for so long.
Congrats! Even if you decide not to take it, it should feel really good to get the offer. Fed jobs are so competitive right now. That's a great feather in your cap.