Going through some files today, I stumbled across this from Thomas Bonk's excellent story on the golf ball that appeared in an April L.A. Times article:
However, there are indications that the golf ball technology — and probably the same advancements associated with large-headed, thin-faced drivers — have actually peaked. Only four players are averaging more than 300 yards in driving distance this year — Scott Hend, Brett Wetterich, Tiger Woods and Hank Kuehne, though it is conceivable with warmer, drier weather and firmer fairways as summer approaches, that number will grow.
Definitely conceivable. Since late April, the Tour average is up 6 yards and 24 players are now averaging over 300.