Felix Domke a famous hacking expert gave a speech at the 23c3 Chaos Communication Congress in Berlin. About 8 minutes into the speech Felix starts talking about the Wii VS PS3 in terms of power, speed, weight and even fun.
After doing benchmark tests on both the Wii and PS3's CPU it was found that the PS3's Cell processor which is over 3GHz was only about equal to a 1.5 GHz CPU. While the Wii's Broadway chip was about 8oo MHz. If benchmarking is to be believed, then the Cell processor is less than twice as fast as the Broadway. More tests should be made but this is a interesting find no doubt.