Well, maybe all the PSP games in the top 10, but that's unlikely to last.
Not like this maybe but I think it's setting a trend. The PSP has been selling well this year in Japan and even now is 200.000 sales ahead of the DS/DSi. Normally this wouldn't necessarily mean that software for the system is also picking up, but the Monster Hunter social gaming trend is putting PSP games back on the map for third parties more than anything and I think what you see in this list is actually representative of the PSP regaining popularity as a gaming system. Of course its presence in the top 10 is skewed because there's a much smaller amount of games being released versus the DS in comparison to the amount of units both systems have out there. But the PSP can do some things the DS can't, and when people are looking for something new after three years of DS, the PSP can be an attractive alternative with a lot of extra media features.