Steve Fawkner, CEO and president of Infinite Interactive, confirmed with Joystiq that the PSP game would only be available as a PSN download -- there will not be a UMD version. "Although we've received great support from D3 and Namco for all previous Puzzle Quest releases, PQ2 PSP is the first Puzzle Quest game that Infinite is doing by itself, without a publisher, so we're not really able to handle a full UMD release at this time," Fawkner told us. He went on to say that "it's important to get a PSP version out there for all the people who enjoyed the original PQ on PSP and wanted the second one."
Fawkner offered further insight into why Infinite would be publishing the PSP version itself (given that other versions were published by D3). "The truth is that most publishers really aren't keen to take a risk on PSP these days, which is kind of sad, because it's 'taking risks' that gets great games like Puzzle Quest published in the first place!"
As far as features go, Fawkner also confirmed that Puzzle Quest 2 for PSP would not include multiplayer. The multiplayer mode in the first Puzzle Quest was apparently not so popular among PSP players, so the team decided to focus on implementing Elite Mode (a tougher version of the single-player game that yields better rewards) into the PSP sequel, which it thought would be a better fit for the PSP demographic.