Planet3dnow.de have posted an In-depth guide that takes a look at the AGP 3.0 specifications! Here"s a snip.
AGP 3.0 is the third generation of accelerated graphics for the Intel-compatible computers and will be officially introduced on 11/12/02. In contrast to AGP 2.0 the AGP 3.0 specification isn"t just a derivation of an existing standard. AGP 3.0 is incompatible to AGP 2.0 – in theory. However, compatibility can be forced by implementing the "Universal AGP 3.0 Motherboard" standard. Another major difference is, that most of the specification"s enhancements are quite irrelevant for the gaming community, whereas the professionals will be truly grateful. Intel states in its specification, that most of the enhancements are specifically for workstations and professional users.