Illegal transport "socket.io.js"

We're trying to running socket.io with Express. The code is the following : http://gist.github.com/601921
But we get a weird error when fetching content at http://0.0.0.0:3000/socket.io/socket.io.js

Any idea what is going on? That's quite annoying.
Express version : 0.2.5
Socket.io version : 0.5.3

[SlNPacifist]

It can be related to the commit http://github.com/LearnBoost/Socket.IO-node/commit/d2ead47fcaff1d0b047a92b689bd70f653277d10, after which Socket.io server was failing to give .swf. Try updating )

[johnnynia]

I experienced the same error. After uninstalling version 0.5.3 previously installed via npm I installed the newest version using git, now it works.