In some games (I don't remember which ones) when you press the PS button and go to the Photo column a 'Screenshot' button appears. I think in some games like Metal Gear Solid 4 you can even plug in a usb keyboard and press Printscreen.
I don't have any coding/skinning skills but I am very much looking forward to seeing a new menu for the ds2. I would gladly donate some money once some more progress is made.
to everyone working on this: keep up the good work!