BeanShell already has a "server" mode that supports browser (using an applet) and telnet clients.

Although multiple clients will share the server space, they can't see what each other is doing, or typing, like in an Instant Messenger window.

With this simple enhancement the server mode could become a very powerful collaborative development tool.

There is a similar application for Phyton, see :
http://sourceforge.net/projects/playsh
http://www.wired.com/news/technology/0,70413-0.html?tw=wn_index_3