It should probably be noted that what's actually going on here is that there's some issue in the Erlang runtime that's hurting it substantially on the quad-core

It should probably be noted that what's actually going on here is that there's some issue in the Erlang runtime that's hurting it substantially on the quad-core box. On the single-core benchmarks, it speeds up substantially and is neck-and-neck with Haskell. Partly there's an issue here that the priority for Erlang has always been more multi-box distributed systems rather thaan single-box concurrency, and partly there's an issue that Erlang's not-really-open-source nature seems to hold back progress in fixing issues like this. And, partly there's the fact that the Erlang core team doesn't really care at all about micro-benchmarks like this.