The first "offical" reviews of the Geforce 9800 GTX are appearing on the web as the NDA from Nvidia falls. German site PCGH.de has a lot of benchmarks from synthetic benchmarks like 3DMark 06 and games like Crysis, Call of Duty 4 and UT3. They even check 3way SLI, something the 8800 GTS cannot do.
As a summary, the 9800 GTX is a nice card but not if you go higher in resolution. With 1.680x1.050 and 8x FSAA upwards, the 9800 GTX has problems with the low memory bandwith.