It wouldn't even need to be multithreaded, I don't thnik. You could have some green threads-type system, using asynchronous I/O, a single-threaded server, and something along the lines of Lua's yieldk. Have a new script spring into life for each connection, suspend it when an I/O operation starts, and resume it when the results are ready (or when something goes wrong). I think this will be what Erlang does.
(I'm sure there are potential problems with this, but hopefully it would be overall no worse than the current situation, while being easier to work with.)
