This would make an awesome learning tool for schools and such. Make it into some kind of appliance, add a bunch of examples, problems, tests and such and it can teach kids collaborative debugging and the basics of programming.
If I had to guess it's running User Mode Linux (or some similar jail) and ptrace (or some similar systrace or syscall tracer).
I poked a bit with perl "Config" (eg: perl -V) and it looks like they're running Gentoo.. all accounts seem to be on the same instance (nobody). So it's most likely a jail.