Have you considered JavaScript Spidermonkey or JavaScript Rhino?
Sandboxing is automatic, and lots of people know the language already
(although fewer people are familiar with its dynamic object-oriented
capabilities).

Tony Belding wrote:
> I'm interested in using an off-the-shelf interpreted language as a
> user-accessible scripting language for a MUCK.  I'm just not sure if I
> can find one that does everything I need.  The MUCK must be able to
> call the interpreter and execute scripts with it, but the interpreter
> must also be able to call functions in the MUCK code.  And then there's
> the security issue that really worries me. . .  I have to be able to
> limit what the interpreter can execute.  I can't have my users running
> scripts that access the console, access the filesystem or sockets
> directly, or call libraries or other binaries outside the MUCK.
>
> Is this practical?  I'm thinking of Ruby or Python for this, if they
> can meet the requirements.
>
> I might even consider REXX. . .  I remember ARexx from my Amiga days,
> and how great it was for string manipulation and application scripting.
>  However. . .  My immediate target platform, Mac OS X, comes with Ruby
> and Python but not REXX, so that's a disadvantage.
>
> My final option would be to create my own language interpeter where I
> have control over everything that happens.  That is what MUCKs have
> always done in the past.  But the result was always quirky, limited
> languages like MUF (Multi-User Forth) which really turn off a lot of
> coders.  Furthermore, I've never created a language before, and it
> would be a lot of extra work for me.
> 
> -- 
> Tony Belding, Hamilton Texas