I've been asked about OpenCV with the Rift a few times, so I've made the example code for doing Rift rendering of captured OpenCV images the subject of my latest video.
A walkthrough of an application that pulls images from a live Rift mounted webcam and renders them to the display.
Example source code
Full example repository
Brad Davis - Developer for High Fidelity
Co-author of Oculus Rift in Action