Walker Books (@walkerbooksuk) have just tweeted:
Exciting news! The Judy Moody movie, Judy Moody and the NOT Bummer Summer, will be released in the US on June 10, 2011...
No date yet for the UK.
See also http://www.judymoodythemovie.com/ and check our catalogue for Judy Moody books (by Megan McDonald).
PS 3/3/2011, article from USA Today