Texas Instruments OMAP3430 processor, based on the ARM Cortex-A8 architecture. It also seems I misread the website. the 3440 is clocked at 800MHz, while the 3430, the droid's is stock at 600MHz. But, newly designed models, such as the 3640, are stock at 1GHz...so there are phone processors that are reaching the 1GHz area.
On a side note, the Google Nexus One and Acer Liquid phones run a Qualcomm Snapdragon processor clocked at 1GHz.