We confirmed that Nvidia G84, Geforce 8600 series won't go to AGP that soon. The current bridge chips are not compatible with the G8x chips and Nvidia has to make the new ones. AGP versions of these cards might be delayed for at least three more months.
Our well informed sources confirmed that Nvidia still didn't order the new bridge chips. It takes two to three months to get the chips out of the fabs, probably TSMC and by that time the new PCB's should be designed in order to support the AGP interface.
ATI's cards are still scheduled for some time in late May.