It looks like he did, along with a lot of other pathetic Georgia Republicans. At first there was some skepticism that this was legit, but so far there have been no objections from the Barr camp. Barr was considering a run for Congress as a Republican, but recently announced he wasn’t going to run. But he does seem to be attempting to re-ingratiate himself with the GOP.
On a larger scale, this mass endorsement by elected Republican officials seems to indicate that establishment Republicans are coming to terms with the fact that Gingrich is the last remaining alternative to Romney. Of course there is still Ron Paul, but these types of Republicans are too fearful and/or wishy-washy to endorse a real alternative like Paul.
Update: The “some skepticism” link above was incorrect. It is now fixed.