I would argue that developing a handheld MMO could be the largest challenge in game development. For example, the game needs to be developed from the onset to address limited communication tools, screen real estate and controls, which are all intrinsic to providing a quality MMO experience. We have a number ideas and solutions to address the above-mentioned concerns, but can't go into those details right now.

Sony has shown a commitment to developing robust console hardware with strong longevity which is crucial to any viable MMO console strategy. In addition, Sony understands that our MMO business model is different than the traditional console model and is giving us the flexibility to develop and publish AAA MMOs.

In Tabula Rasa, we've worked very hard to make your character's attributes and equipment less of a focus then they typically are in other MMO's. We also wanted to make content accessible through story and accomplishments rather than through leveling. Because in Tabula Rasa we have tried to downplay the importance of leveling, players can instead spend their time focusing on gameplay instead of manically grinding to reach new content.

Via JoyStiq