Celebration V - August 12 - 15, 2010 - Orange County Convention Center - Orlando, FL
Celebration Japan - July 19-21, 2008 - Makuhari-Messe - Tokyo, Japan
Celebration Europe - July 12-15, 2007 - ExCeL Exhibition Centre - London, England
Celebration IV - May 24-28, 2007 - Los Angeles Convention Center - Los Angeles, CA
Celebration III - April 21-24, 2005 - Indiana Convention Center - Indianapolis, IN -
Celebration II - May 3-5, 2002 - Indiana Convention Center - Indianapolis, IN
Celebration I - April 30-May 2, 1999 - Wings Over the Rockies - Denver, CO

Does anyone have an idea the next Celebration is?
It looks like there is multiple years between them, except outside of the US.