Just so you are not under the wrong impression, though you CAN create a game for the PS3 using the PS3 linux kit, its not like you will be able to package it up in such a way to realisticaly SELL it (or distribute it for that matter). I highly doubt the majority of PS3 gamers will have or make use of the linux capabilities, yet alone purchase games for it. You will not be able to just hand your friend a CD-rom and have it play in their PS3. You wont be able to produce games anywhere like what you would technicaly see on these next gen systems either, and the work necessary to get anywhere near the power of the PS2 would require so much work, that a $100 drop for XNA will seem pitifully small.

XNA is (arguably) going in the direction to EVENTUALY allow people to allow smaller developers with XNA games to publish over their xbox live, but they arnt there yet, and may never be. PS3, to my knowledge, offers no such thing. I have not confirmed this, but with Wii's operah browser and the use of Flash, may be, sadly, the most viable commercial shot you would have without the Sony/Microsoft/Nintendo's support of your project.