TryPerl is a cloud IDE for Perl. It's still a long standing work in progress.
Check it out live : http://www.tryperl.com
Currently it doesn't execute code. (I know this seems very pointless).
I did however, make it work in the past with FreeBSD jails, Linux Containers and other crazy things but (like you guessed) there were security holes and I couldn't fix them.
I'm not giving up though, I'm learning something new everyday and hopefully in sometime I will have enough expertise to write a debugger/tracer executor program that will use ptrace to inspect and run a program and shut down anything malicous.
If you think you can help, please email me at gideon at cpan dot org