The current iMacs are designed around Intel's mobile platform.
In late April / early May, Intel releases the next version of its mobile platform, called
Santa Rosa. The release of Santa Rosa will be accompanied by new Core2 Duo mobile processors, including the X7800 (2.6GHz) @ $795, the T7700 (2.40GHz) @ $529, the T7500 (2.20GHz) @ $315, the T7300 (2GHz) @ $241, and the T7100 (1.8GHz) @ $209. All of these processors feature a 4Mb L2 cache and use a 800MHz bus, except for the T7100 which has 2Mb and the older 667Mhz bus.
[Look for these in the Mac Mini refresh too.]