Yup, it's confirmed, he just signed a one year $8 million dollar deal to return to the Braves.
After turning down a $13 million option with the Mets for 2008, taking a $3 million buyout, he turned his attention toward the Braves. He gave Atlanta a hometown discount, agreeing to an $8 million, one-year deal that was the lowest he was willing to play for and wasn't available to anyone.
http://sports.yahoo.com/mlb/news?slug=ap-braves-glavine&prov=ap&type=lgns