My simple Perl todo script (either writing or reading a text file) causes the "maybe" program to fail while partially reading/outputting the todo archive file.
At this point, it will only work for the most trivial of demo cases. Still IMO it's a cool demonstration of the linux ptrace facility. And if the author implements the missing sandboxing/emulation layer in a future version and switches to whitelisting instead of blacklisting syscalls I think it could actually run a limited number of programs (forbidding stuff like mmap and network IO).