Just linking processes together is not enough to build a cluster. How do you allocate the physical resources, deal with network splits, package and deploy new code, monitor... There's a whole layer that's missing there that would surely be nice to have. The OTP framework could even be used to sandbox in LXC and start other type of applications.

That is what LING (formerly erlang-on-xen) is here for: http://erlangonxen.org

It's pretty cool but I don't think that it's open-source.