Get the Zune software The software will import all your iTunes music. I've never bothered to try and jailbreak it. There is a developer community, but it's been pretty clear zune is being pushed into the background in favor of Win Phone, so I don't think it's a very active community.
I use my Zune HD more for audiobooks than music. If you use Audible it's a supported device. If you already have audiobooks, you can use Overdrive to get non-DRM audiobooks onto your Zune
Zune pass is pretty awesome for music at $15 a month. You get (almost) unlimited access to the music catelog, and you get to keep 10 songs per month as non-DRM MP3s.