It was originally drawn in various pieces by Wally Wood to remind himself to stay on his toes. Later it was compiled and used by Wally Wood's assistants to help them emulate the master.
The full-sized, high-resolution version of the image below can be found at Joel Johnson's blog. Joel came into possession of the original paste-up and has generously scanned it and shared it with the world There's a lot of cool backround information about this legendary cheat-sheet at Joel Johnson's blog.
Hey Joel...Thanks!