Logged in just now and found that I have been banned.
iXtreme Lite-on 1.6 (flashed with connectivity kit)
I have never played a Wave4 game
I have only played two backups on Xbox Live (CoD:WaW and GTA4,) and even then it was for less than a month.
The few games I play offline are all ABGX verified.
I did play Beatles Rock Band prior to the release date, although I was not connected to Xbox Live at the time, I have a feeling that this flagged my account and caused me to get banned upon connection.
I'm not horribly upset, since I didn't play on Live anyway. So the only loss is on Microsoft's behalf since now I will not be buying any more DLC or XBLA content from them.
Sadly, this means that I will need to purchase Modern Warfare 2 on PC in order to get my multiplayer fix.