Does (or can) Jurassic also supported interpreted execution mode, where IL doesn't need to be first emitted and JIT'd?

Also is there ability to restrict resource usage by the script - eg. cpu, memory that sort of thing?

Thanks

Nope, sorry, Jurassic only supports compilation and not interpretation.  There are no resource limiting features per se, so you are limited to what .NET provides.  I believe .NET does allow you to limit memory usage and CPU in an app domain, but you can only do it via an unmanaged host (see http://msdn.microsoft.com/en-us/magazine/cc163567.aspx).