I've always loved jazz but have never actually been able to get into it. I don't think I've ever heard a jazz song I didn't like, and I love the concepts of it, I just don't really know where to start. I'd like to know how to really get into listening to jazz, and more importantly, how to play it! I know a little bit amount of theory, but probably not enough to be comfortable improvising in a jazz song. I know how chord progressions work, I know the famous ii V I progression, I know scales, I know how the awesome 7th-13th chords work, I just need help pulling it all together and getting it to help me get into jazz.

Also, I'm actually probably more interested in learning jazz piano than jazz guitar, but really all I'm looking for are some resources on how to really get into jazz :p
get a fakebook and look through it
Those ABRSM piano accompany books are pretty good too.

The best way to learn jazz is to play it, and know what you're playing.

Learn why ii, V, I + substitution = almost all jazz standards.
You could always try transcribing some of John Scofield or Wes Montgomery's music. I've been meaning to do that, but I feel like I'd be getting ahead of myself there. Soon enough, though.