So here are the binaries I was talking about in my last post.
You can upload lua scrips to your NDS and run them, all via wireless.
Then you can access the DSerial, sockets, save through dldi, keypads, touchscreen...
Examples included:
Robot.lua: skeleton to access the DSerial
Server.lua: a simple web server in a few lines of code
http://aguaviva.googlepages.com/LuaDSerial.zip
Source code is available upon request.