I read something about that too but didn't really understand it. I'm sure I read that the Sky stores a record of which games have been installed and even if you format the SD card you can't install different games. Is that really correct?
That was true for the original release, but they've since released another version of the card without that bullshit. You can tell which is which by the color of the button, but I forget which color is which version. There are ways to hack the older version I think as well.