I have been driving all over places east of Atlanta since getting my Thunderbolt about 4 weeks ago. Been seeing intermittent 4G signals in places VZW does not show 4G coverage. Some of it undoubtedly was getting line-of-sight to a 4G tower, but other places were probably due to testing by VZW. Their July 21 roll-out list is quite large. News.VZW.com is their press release site, and they had over two dozen June 21 press releases for the July 21 date.
Baton Rouge is on their "coming soon" list, but I didn't see a 6/21 press release on it.
4G at some point may be like EvDO, they may just start activating it without much fanfare.