Being that both systems use processors with similar die sizes that were produced using the same process you would expect them to perform in a similar range ...
For the most part, any performance difference we have seen between these two systems has had the PS3 performing worse. I suspect that this is mostly caused by the PS3 being more difficult to develop for, but I would expect that the best the PS3 can ever really hope for is to reverse the perfomance difference over the XBox 360.