There was definitely some updates to the 3.0 PHB. For instance my copy, which was a second printing, had diagrams from Dragon magazine further explaining AoO's and how they worked. I don't know for certain if any errata was incorporated to the PHB's but I think that there was.
I'm holding out on buying the 4E core rulebooks in the hope that WotC do something similar with 4E. There is going to be errata of some sort and I would prefer to have the later printings of the core rulebooks that incorporate some of that errata.
Of course WotC haven't said that future reprints will include errata. And it would be silly of them to do so since it would encourage people to buy the 4E core rulebooks later, instead of now.
Having said that I still hope that WotC include errata in later reprints.
Olaf the Stout