Well, the bad news is that I can't say if the PSP-PS2 link unlockables are available on the Xbox version because I haven't tested the latter. My instinct assumes they would be because the link-up unlocks are no different from the other unlockables in the game (and therefore don't feel like super-duper bonuses). But I couldn't say for certain, sorry.
But I wouldn't consider it a deal-breaker because the bad news is that the unlocks are not very interesting anyway; unless you are a super-duper completist, of course.
On the other hand, the bad news is that the Xbox version apparently does not work on Xbox 360 and I've not heard of a 360 version yet.
Having said that, the bad news is that you will need to upgrade your PSP firmware to at least version 2.6 to play the game on Sony's handheld.
The good news? Power slides are fuuuun!
