He was posting short blurbs for a while at ABC News Radio. But the Associated Press reports he's now jumped in in a big way.
"Whenever I've seen one of those 'Gun-free Zone' signs,' I've always wondered exactly who these signs are directed at. Obviously, they don't mean much to the sort of man who murdered 32 people just a few days ago." -- former Sen Fred Thompson (R-TN) blogging at National Review Online
In addition to National Review Online, his posts are turning up with greater frequency on RedState.com and on his ABC Radio blog, the Fred Thompson Report.
It's an interesting way to join the debate, without jumping straight into the GOP race.