If what was said about the Cell turns out to be true, it has the potential to be significantly more powerful than both the Xbox360 and the Nintendo Revolution. In theory, the Cell will be a much more powerful chip.
One thing to note though is how that will affect games. The Cell might be the more powerful chip, or the most "capable" chip... but we have to see how it actually gets used.
I'll wait to see what the games actually look like. It's great to say the chip is 2345345x faster, but if the games don't show it, what is the point.