Looks like the axe is falling on those dudes now.
Here’s the news you’ve all been waiting for – Microsoft WILL BAN 360 firmware hackers. The confirmation comes from a user who claims his unmodified 360′s were banned from live because the Mac addresses reportedly denoted his systems were modded. To further confirm, a member of Xbox support staff has said that they are looking into the issue.
Source, thanks to Kamen.