The British Board of Film Classification has revealed some details about the upcoming Genesis collection for Xbox 360 and PlayStation 3. In
their report on the content, they mention 40 games (those are the ones revealed on Sega's site already) and a list of unlockables and bonus content: 9 more games, 8 video interviews totaling 30 minutes, and 45 minutes of game play footage.
This still doesn't reveal what the unlockable games are, but at least now we know there are 9 of them. 45 minutes of game trailers seems a bit excessive, though. I wonder if Sega is really that hard up for advertising.