Assuming i could afford it, i'd buy the PS3, the wii is a gamecube with motion-sensor controllers, the graphics aren't anything special to look at, and the games are, in their majority, too childish. The PS3 is only just started, and it's games list isn't anything special to look at yet, but it already has PSP connectivity and a whole onslaught of awesome games in the works for it.
(Gundam Musou, Devil May Cry 4, Metal Gear Solid 4, etc..)
This said, the PS3 is too pricey, true enough, but i won't waste my money on a Wii either, plus, give it 1 year so the blu-ray format settles in, production prices go down and so will the PS3 price tag. by next year's Christmas it will be at least 100€ cheaper. Bet on it.