(FT 5) UPDATED: Panasonic DMC-GH1 sold in Japan by the end of April
It seems Panasonic has anticipated the time and they are ready to sell the GH1 camera at the end of April (instead June). I believe they were forced to do it because of the introduction of the Canon 500D /T1i.
Source: chinese website (translated in english)
Source: japanese website (translated in english)