According to the NY Times:

But, on July 31 the “Friends of Fred Thompson” committee will go public with that information when it files a report of contributions and expenditures through June 30 with the Internal Revenue Service, according to Burson Snyder, a Thompson spokesperson.

The Thompson camp isn’t saying if he plans to announce at that time or not.
Whether or not he announces it will be good for his supporters to see if he’s going to be a viable candidate or not. There’s a lot of hype on the Internet over his candidacy, let’s see if the money lives up to the hype. If it doesn’t, conservatives may need to draft someone else 🙂 and no it won’t be Newt!