The OpenGL in Vista *BETA* is a wrapper to D3D, version 1.4 and no extensions (this means that the function set will only include core 1.4 functions. Which sucks for games, of course).
And about half as fast, of course.
ICDs will work, as taylor said. But if Microshi Microsoft provides IHVs the info necessary to write drivers that work with the Vista desktop, they could easily do it. I'm guessing that MS just didn't want to do this in the beta stage yet, and someone simply panicked, and thought that MS is going to try to kill OGL (this wouldn't be their first attempt). First of all, in the EU at least, MS can be forced to provide software developers the code required to make their applications fully compatible with the operating system (just like MS software). Second, OpenGL is still the api of choice in every field except games. MS put OGL support into Windows NT to lure customers who needed OGL for professional simulation away from other operating systems. But, at the same time, they wanted OpenGL to stay in that field and never come to the gaming market, where they wanted D3D to be the only api (which was optimised for software rendering, and sometimes this origin caused problems when 3d accelerators came out, e.g. the way D3D stored vertex information was not optimised for modern 3d cards, while OpenGL's method was). So they told everyone that OpenGL was too slow for games, and was good for CAD only, whereas D3D is not as precise as OGL, but faster, and therefore well suited for game development. Which is of course BS.
D3D has been improved to the point where the difference in performance is very small, and depends more on the game. (I'm guessing FSO is optimised for OGL, right?). BUT all that effort put into making a software 3d api into a modern 3d api comparable to OGL in performance is just a waste. And I still hate D3D's approach to coding, where you have to decide what code will be best suited for the target machine. OpenGL does that for you (you give hints to the driver, like GL_Hint_Fastest or GL_Hint_Nicest). This requires a good driver of course, but NVidia has a habit of making good ones. And the less code you write, the less you have to debug, and the faster you'll be done.
If I had to choose between compositing and nice glass effects and opengl, I think you'll guess which one I'd choose. But I really doubt I'll have to make that choice
