I'm thinking it might be prudent to wait for Open GL 3.0 before upgrading my 7800 GT. It still performs phenomenally well, and I'm not suffering for lack of power when developing my own projects. Still, I'd like to eventually upgrade.

I would upgrade to a 8800GT. Nvidia already stated that all 8 series and higher are going to support opengl 3.0. So don't really expect new hardware to ship it will just be a driver update that makes 8 series and higher support opengl3.0. The functionality is already on those cards.

From my understanding, opengl 3 will mainly be providing extensions for hardware features that are available in dx10. So if the card is dx10 ready, it should work with ogl3.

Correction not extensions a whole rewrite of the api lol. Yes OpenGL 3.0 is basically bringing OGL up to the erra of DX10. So in all reality with a DX10 card and a driver update for it you can use OGL 3.0 when it comes out. Whenever that will be :S

dear god.. so much wrong here it is silly.

OK, so as of the best information we have, OpenGL3.0 is going to be an API rewrite but for DX9 level hardware. A later version of OpenGL3.x was going to be for DX10 functionality.

Note; best information we have. Due to a years silence and a rumor of a rethink it could be that GL3.0 is DX10 only, however I personally doubt it, more likely we'll see the two levels rolled out at once.

More information will be around at SIGGRAPH.