MS arn't the only ones using the PowerPC.
Sony, Toshiba and IBM's "Cell" works around a PowerPC chip with the PS3, also IBM and ATi are helping Nintendo design its guts of the "Revolution", with it also being rumored to have a PowerPC chip.
Also, MS have sent off modified PowerMac G5's as early dev. kits for developers of the Xbox 2, old news but some people might not know yet...