Her gamertag for Saturday, you mean? Because after Saturday, you'll never see it online again.
To be fair, Megan Fox is a confessed gamer - (an actual GamerGrrl, I believe), but it would be insanely unlikely that she would make her gamer ID available for public consumption - any more than Joss Whedon or Felicia Day do.
Somehow i always doubt such statemens.. it's akin to boygroup or girl group members always being single yet when they disband suddenly the truth comes out that many of them have had partners but had to keep them secret for marketing purposes.
I suppose it could be true though because after all they are people too and like to spend an evening just rocking away on their console.. there are many stars who are proven gamers (Vin Diesel and Robin Williams come to mind).