I've been giving this a lot of thought - recording live instruments at 88.2kHz to capture "more air" or harmonics and then a nice downsample to 44.1kHz.
What I found interesting whilst "Googling" is that a post on the Nuendo forums claims that mixing in your DAW will sound better at 88.2kHz as well.
The claim is, that many plugins work by sample rate, even if they say they are working in milliseconds. Therefore, your plugins have more to work with or something. (I would assume that this would only be with 88.2kHz source material though?)
Has anyone ever of heard of this? And is anybody mixing at a higher rate than 44.1kHz?