Yup, we're working on a level editor :) For couple of days we've been gathering limited feedback in the official forum thread, now it's time to expand it a little bit and get more people in.
The editor can be a bit tricky to use, so we made a video of it's current state, check it out:
http://www.youtube.com/watch?v=2jlXPbVMpvM
If you'd like to test this out, and most probably have your levels lost eventually -- head over to thefeedback thread to participate.
Also, we're preparing for GDC. We thought it'd be fun to have actual comic books there with SpeedRunners characters, we'll be revealing some of the comic books in the announcements. Here's the first page of Hothead's comic book: