I always say, bring out games to as many platforms as possible! The more people enjoying a game the better.
There is only one thing that bothers me with this, do it right and take advantage of the platform specifics. Don't concentrate on the weakest part in the chain (e.g. XBox) and export it from there. Instead make use of the strength of the platforms (e.g. remote controls of the Wii).
I'm fully aware that you can't finance making games that platform specific, but if you have to choose develop it for the PC and export it to the consoles, not vice versa because than you nearly always get a bad result (e.g. Halo, Gears of War).
The phone is ringing and I cannot linger. So, look out, butt, here comes my finger!