I was lucky enough to get a copy of GPU Gems for my birthday a couple of days ago, and it’s got some really nice articles in it. It’s tiny bit nVidia-biased (understandably, since many of the people writing for it were from nVidia), but not anywhere near as much as it could have been. The main issue is that nVidia cards do some automatic depthmap trickery (in shadowmaps) which ATI cards don’t do, so those chapters would need to be scrutinised more closely for compatibility issues, but otherwise it’s pretty generic stuff.
It has some great discussions of techniques that aren’t necessarily viable in mainstream products yet, but may very well be in the near future. It’s also full-colour throughout, which is a first for a graphics book (I think - normally they just have b/w pictures and a set of colour plates in the centre) and I think really adds to the book; diagrams are so much better in colour.
Some of the stuff won’t be new to many people who are up to date with graphics techniques, but most of it is pretty leading edge. I believe this book is unique in that it brings together lots of information you’d otherwise be harvesting from lots of disparate and less well edited academic papers. Well worth it.