If still interested you might want to check http://slxslchat.slx.cc/

This guy's written a client that allows in-world chat via a text interface and done it in two parts, a transport that does the communication and a front-end user interface.

I am guessing it's not too difficult to get the transport running on the N900 so this then becomes a nice little project in creating a UI.

Also, it seems the transport doesn't have to be on the same machine as the UI, so if you have a server on the Net somewhere you could run the transport on that and keep the N900 component nice and light.

Could be a good fast way to get a sparkle-style app running on the Nokia.