According to GI.biz, Q Games founder, Dylan Cuthbert, has said, on Twitter, that:

I don’t think we’ll port anything else to the PSP, we have to see how [PixelJunk Monsters Deluxe] does as there’s a lot of piracy.

So right now, due to open chats of piracy of the game and whatnot, development of future Q Games titles showing up on PSP largely depend on how many people actually purchase the game, seeing as piracy, to them anyway, is a serious problem. I know a few of you really look forward to seeing their titles on the handheld, I just hope you get legal copies of the game if you want them to bring others over as well! Hopefully they’ll find something that would be an effective anti piracy technique, though.