basic IR motion tracking

came across this little IR proximity sensor

just wondered if anyone had experience with simpler for basic motion tracking with the Arduino?

Not specifically, but have a read of this page:

http://letsmakerobots.com/node/4428

I have had a lot of success with the QRD1114 (datasheet). See my old website for an example project for a robot line detector tracking. The included software is not for the Arduino but the hardware can be reused.