An early project to integrate accelerated 3D into XFree86 3.3. The primitive architecture of UtahGLX makes it slower than the DRI but it is much simpler to implement and is also easier to write drivers for. This meant UtahGLX was available earlier than the DRI and with a greater range of supported 3D cards. UtahGLX is still the only available option for accelerated 3D under XFree86 3.3 unless you have a Voodoo based card.
Most of UtahGLX is based on earlier Mesa code. Some of the work is the DRI work, and some is the Mesa work. The Mesa work will transfer over reasonably well. The DRI work is mostly initialization and kernel drivers.