I didn't see it on the forum, so I post it. It was a nice event last year and it will be on the whole week-end this year.  (actually can't do it as I'm got my friends BMX race (I can't miss it, they come from Thurgau for the race...)

the festival will be held on the week-end (24-25 march) in Versoix. (9am to 6pm on Saturday and 1am1 to 5pm on Sunday)

note that on sunday children less than 12 yo will have an eggs hunt and if you like soccer, a delegation of the Servette FC will be there around 1.30 pm

More information (in french, sorry) http://www.versoix.ch/fdc.php?page=114

and some pics  from last year ...