This is from Bob Barr's campaign:

Former Georgia Congressman Bob Barr will hold a press conference on Monday May 12 to discuss his future plans and the 2008 election. Rep. Barr launched an exploratory committee last month to determine whether he should file as a candidate for the Libertarian Party’s presidential nomination.

Who: Former Georgia Congressman Bob Barr
What: press conference
When: 11:00am ET on Monday May 12, 2008
Where: Zenger Room at the National Press Club, 529 14th Street, NW, Washington, DC

[UPDATE] Politico reports that Barr is running.