Friedrichafen event is only held every TWO years
Last one was last year (2007) so mathematically it will next be staged in errrummm ... 2007 + 2 (counting on fingers) = 2009.
In 2007 it was held in mid April so expect roughly the same period in 2009.
A terrific event well worth a visit. Stomped around for two days and couldn't get enough of it.