The test was well documented and concludes that "the G5 has about 22% better scala r floating point performance per clock cycle than the G4 systems tested and 32% better floating point performance per clock cycle than the P4 systems tested."
Even more interesting is that NASA's benchmarks come close to mirroring Apple/Veritest's results for SPECfp_rate_base2000. Apple's benchmark lists the dual 2GHz G5 as having a 194.5% performance advantage over a 3GHz Pentium 4.
NASA's study found the Dual 2GHz Power Mac G5 to score 498 MFLOPS for their Jet3D performance. A P4 running at 2.66GHz scored 255 MFLOPS: a 195.3% performance advantage for the G5 in this test. The performance advantage can be expected to change only slightly against a 3GHz P4 as NASA expects a 20% increase in performance for the G5 would be reasonable "when G5-aware compiler tools become available."