Here's an idea: what about using the a/v port of the N900? It samples at 44.1 Hz 16bit which should be more that enough to sample IR remotes etc. The only thing needed is a sensor to capture from the sender and output it as an analog signal. All you need to do is pick up the data that comes through the N900's audio in and process it.

Would be relatively straightforward to modify the driver to export the raw IR and IR+visible values. The sensor does indeed provide both.

Given the fact that it would need power and electronics, it'd be kinda odd. But such dongles exist for PCs and the data can be carried over, it's how lirc bdatabases are built. It's much easier and a converter is very simple, and it draws power from the serial port on any PC.

Why not remove the IR-blocking filter on the camera and use it ?