Overkill? *me counts to 10 slowly so I don't explode* There's no such thing as overkill when it comes to resolution. At least if you're talking about raster-based graphics. The day I can get a cheap 600ppi monitor is the day when using an extreme resolution is overkill.
Do you use antialiasing and anisotropic filtering on your games? Well, using such a high resolution is a great way of not needing to use any AA and lower quality AF. Most games that I run look sharper, with virtually no jaggies or shimmering, than a lower resolution with high AA and AF settings. Not to mention that it actually runs faster in most cases.
And any good 3d game that enumerates devices in D3d or OpenGL like it should will support it. 3dMark works with it, any Q3 engine game does, and I'm pretty sure UT2k3 does too. Only games that specifically check for certain resolutions don't work.
The oldest game that I've tried with this monitor is Shogo, which was released in late 1998. That has support for the high rez too, even though it's only a DX6 game.