There is now an option for Anisotropic filtering in the menu under Options->Video.
Anisotropic filtering basically sharpens textures that are far away and at an angle.
Increasing the level of anisotropic filtering will increase the CPU load.
These pictures demonstrate the effects of anisotropic filtering on txnex03:

No anisotropic filtering:


2x anisotropic filtering:


4x anisotropic filtering


8x anisotropic filtering


16x anisotropic filtering

Here is a little wikipedia article about anisotropic filtering:
http://en.wikipedia.org/wiki/Anisotropic_filtering