This topic doesn't have a dedicated page yet. For now, here are the links I've gathered with this tag.
How to shuffle songs? - Spotify Engineering : Spotify Engineering
I used to talk about randomness with my students when I taught maths and we specifically talked about how the iPod shuffle had to be de-randomised in order to make it feel more random. Interesting that Spotify seem to be coming to the party late here - one of those situations where we don't have a lot of history, so we have to reinvent the wheel?