blog has gotten its hands on an AMD Phenom X4 GP-7000 and has run some benchmarks on it against an Athlon 64 X2 6400+, and the results aren't what you'd call great.
It's a slightly unfair comparison, though, as the Phenom X4 GP-7000 is only clocked at 2.0GHz, compared to 3.2GHz for the Athlon 64 X2 6400+, and the Phenom is a quad core part.
The motherboard was based on the AMD RD790 chipset and 2GB of Corsair DDR2-1066 memory was used as well as an 8600 GT graphics card.
Looking at the benchmark results, the Phenom X4 GP-7000 doesn't look good, it doesn't win a single test in PCMark 05, although it's slightly faster in 3DMark 06; but it's defeated in all the other game tests.
It does better in SiSoft Sandra 2007, but oddly enough, it's only getting about half the memory performance of the X2 processor.
You can find the benchmark results here