I do a lot of listening to music and podcasts with a trusty old second generation iPod Nano running Rockbox. What XBMC is to video playback, Rockbox is for audio playback. (I should get around to writing up what makes it that much better than stock firmware.)
Anyway, I thought I'd leave a note here about the issue I discovered today since it took me several searches to yield anything relevant and I spent a good half-hour or so diagnosing the problem.
When I was listening to something I'd recorded myself, I noticed that the left and right channels were switched. After checking the original audio I recorded on my PC, different headphones, and several different versions of Rockbox I realised it was actually a Rockbox problem. Earlier versions don't suffer from this issue (for example, the much older 3.7.1).
In the end, searching Rockbox's issue tracker eventually confirmed this: the swapping of channels is a known bug, though no-one's fixed it yet. Not a big deal, and the easy fix, of course, is to just switch headphones around.