I snagged one of the HP touchpads this weekend on clearance for $100, so did a lot of people. Depending how much work it is to incorporate into the AppGameKit, I can tell you there are going to be a few hundred thousand people very interested in more apps for these devices because nobody else will be supporting them, why shouldn't it be us?
I wouldn't put it ahead of Android and WinMo but if after that WebOS could be supported (and have the ability to distribute via homebrew) I think there would still be a decent market.