The P10 chip is out and doing quite well in the Pro3D market segment in the WildCat XP boards.
The consumer P10 boards seem to have fallen by the way-side however, much as the once planned Permedia 4 did.
It seems questionable now whether the P10 will ever hit the consumer market, as Creative has released an R9700Pro board.
I doubt the R300 will have had any considerable impact on the P10's consumer release schedula, as the P10 is not intended to compete heavily in the high end gamers market. The P10 is primarily aimed at being a mainstream product with a few innovative features intended to garner attention to the 3DLabs brand name in the consumer market.