What is it?

IR.EXE is associated with Infrared communications software for various hardware accessories such as lego mindstorm and HP 200LX.

What does it do?

Probly the protocol and driver for the IR trasnceiver.

More info:

There are many reports linking IR.EXE with several viruses and trojans. This is because the viruses attempt to terminate processes including IR.EXE
It is not currently "at the time of this writing" associated with malware.