OpenGL is a cross-platform standard for 3D graphics, which works on Unix (including Linux/Fedora and MacOSX), Windows, and even things like web browsers and mobile phones. DirectX is Microsøft's private multimedia system (including Direct3D) that is specifically only for Windows and Xbox.
High-end graphics for gaming are available on Fedora. The only problem is market share. AAA games cost often tens of millions of dollars (and more) to produce. Sadly, there simply aren't enough Fedora users to make it worthwhile for most of these titles to be ported to Fedora. (Think about it this way: Many AAA gaming titles aren't even ported to the Nintendo Wii, when it has nearly twice the market share as the PlayStation3 and the XBox 360.)
There are a few titles that are made available for Fedora, that demonstrate that the capability is there; notably, http://www.idsoftware.com/ have always been fairly good about releasing Linux versions.
As for developing a Linux gamers' community: I think that's great, and I hope that the ongoing growth of Fedora (and other Free Software) will draw more attention from the major game studios over time, but I would not expect to see Fedora-compatible DVD's at Game Stop any time soon, sadly.