Ah, Bang & Olufsen -- I've always wanted to test if the N900 could actually handle one of those. With B&O, the key is the carrier frequency: basically, every manufacturer working with CIR devices has chosen to send their data at a frequency of around 38 kilohertz (or, sometimes, around 56 kilohertz); for various reasons, those speeds could be reached by common and inexpensive electronics components. But B&O (and nobody else, so far as I know), decided to use a carrier frequency of 455 kilohertz in their remote controls.

Technically, it is possible to set the N900's IR carrier frequency all the way up to 500 kilohertz (or, at least, that's what the device driver will accept); but I've never tried it against a real device. Also, there are just very few config files available; I've got one for a "Beo4" remote, which has some TV controls -- let me try to add it in, and see what happens...