The test rig is a powerful machine, and they used fresh, updated installations of both the Windows versions. They did not apply any SSD-specific tweaks, nor did they install specific drivers to further improve the performance of the SSD drives; they used the stock Windows drivers in both cases.
The results show that when it comes to reading, Windows 7 beats Windows Vista in almost every test, but the results do come in close. TweakTown believes that when Windows 7 reaches RTM, the gap will be widened. When it comes to write speeds, Windows 7 is also ahead of Vista on all tests, but the gaps are a little wider here. Windows 7 also uses less CPU power during SSD operations than Windows Vista.
These were just preliminary tests on beta software, without specific drivers, so the situation may get better. TweakTown does say that it's clear that Microsoft made improvements in this area.