NVIDIA has posted some OpenGL-related presentations from their recent NVISION 08 conference. I found the one on the GeForce 8 features and Cg particularly good with respect to introducing some modern OpenGL functionality and giving a sense of direction for the API.
http://developer.nvidia.com/object/nvision08-opengl2.html
Also check out the NVSG presentation with has some OpenGL related content.
AMD has released ATI Catalyst™ 8.9, which includes a number of OpenGL 3 extensions:
The addition of the geometry instancing extensions and of gpu_shader4 (GLSL 1.20) is particularly significant, as they expose functionality that has been available since DirectX™ 9, and of course DirectX™ 10 features as well.
I just stumbled on this Google Code project which is categorizing and documenting OpenGL extensions. It should prove to be a very useful reference, check it out.
Michael Lucas-Smith posted on his blog a list of forward-compatible OpenGL 3.0 constants. This, combined with my list of forward-compatible OpenGL 3.0 entry points, should help people write future-proof OpenGL code.
The Riven X and MPQKit Trac wikis are finally back online. Although development has moved to Launchpad, the wikis still contain quite a bit of useful information, as well as milestone planning and open bugs. In particular, the MPQKit wiki has the MPQ format specification page, which is quite complete.