They are primarily getting Banshee through the Ubuntu PPA, with a moderate number building from source or using other distributions — including 20 OS X users.
They are using Banshee in 36 locales, across 30 languages. Keep in mind the Preference to opt-in is (so far) only translated into 9 languages.
I'm still working on better ways to analyze the data and extract actionable information. I plan to have distribution graphs and such soon. In the meantime, I've posted some more stats here. As we get more submissions, add more data points, and get better analysis, we will be able to identify options nobody uses and optimize Banshee for real-world users.