Comparing quad core to quad core (the only fair comparison, because we don't know how the dual-core Conroe would compare to the QX6800 on these apps).
25% more FSB bandwidth (1333 MHz vs. 1066 MHz)
13.7% more clock rate (3.33 GHz vs. 2.93 GHz)
New SSE4 instructions
Differences in cache sizes are not known.
Except for one app (DivX 6), the typical speedup is 25%. I don't count the 3D Mark Pro Overall either, because it is probably very dependent on the graphics card.
So Intel is getting about 10% performance beyond clock. I wonder how much of this is the faster FSB, how much may be due to cache size differences, how much is SSE4, and how much are other microarchitectural improvements.
I would like to see benchmarks Penryn dual-core vs. the fastest dual-core Conroe.
I don't know how much more Intel will improve the performance, or if they will offer higher clock rates than 3.33 GHz, but in its Quad-Core form Penryn does not appear to offer any significant advantage over Barcelona.
I expect Intel will offer Penryn Xeons with very large caches to maximize performance.
2008 will be the year of the great quad-core parity.
Get ready for the price war.