When I saw this page, I had to take a break. This is a true hack. In the best sense of the word.
Sitting in a walled garden, and only pings get out? Try this on for size: ICMPTX (IP-over-ICMP).
By setting up a server side and a client side, someone has found a way to tunnel IP traffic over ICMP packets, that is, when all is blocked, there is still a way out. Wow.