Exploring Erlang @ C4
Yes, it is definitely caturday.
For those of you interested in learning more about Erlang, I highly recommend buying Joe Armstrong's Programming Erlang and/or read his 2003 ph.d thesis, which is kinda similar in content to his book but is more technical and is freely available: Making Reliable Distributed Systems in the Presence of Software Errors. The thesis is a bit more dense, but it was what really made Erlang "click" for me.
If you want to play with the examples, go to CEAN and download "Erlang/OTP Full (Standard)" at the bottom for you version of Mac OS X and follow the "How do I install CEAN to /usr/local/bin" FAQ entry. Alternatively, if you want to wait longer, you could use MacPorts to download and compile it. Once you've got that set up just run erl from the examples directory in the slides download and it should all work.