While it has not been officially announced yet, the CPL has added HALO2 Xbox to their extensive list of tournaments for the Summer 2005 games!

$10,000 Halo2 Xbox Tournament
Tournament Mode: Teamplay
Tournament spots: 32
Used: None
Remaining: 32
By entering this tournament, you may not participate in the following tournament(s):
- $50,000 Painkiller World Tour Stop
- $100,000 Counter-Strike Tournament
- $30,000 Day of Defeat
- $20,000 WarCraft III

From the CPL registration page!