I finally got animations working! I'm using a Blender to FBX script, along with this fantastic multi-take FBX importer. Apparently XNA depends on the actual FBX API for importing, and the API changed drastically just before XNA 4 released, so they didn't have time to get multiple takes (animation clips) working in one file. This importer automagically splits out the takes from the FBX file, processes them independently, then combines them into the original model. I encountered a bug with the Blender to FBX script, but as of today it's been fixed and committed. You can get the Blender export script here and the importer here. (edit: here's a sample project, including a .blend file, .fbx file, and all necessary code)

There are two main themes I want to nail in this game. The first is giving the player freedom to alter the game world; to literally change the world geometry by performing sweet parkour moves (jumps, flips, slides, etc.). The idea is, to create a wall, you simply jump into mid-air and perform a wall jump as if the wall was there, and poof, it's there. Need to get through that annoying concrete barrier? No problem, slide right through it like it's butter.

I realize the chill music in the video doesn't exactly match the motif of the above image, or the whole game really, but hey, it's just a tech demo. No need to start murdering people just yet.