Thanks for posting! I'm actually updating the cluster right now, and I have a Pi2 version, a Pi3 version (still in testing, not live yet), and a Pi Zero version (very slow, but same thing is the size of a plum!).

I'll be presenting on it at this year's php[tek], and will also post a few YouTube videos and blog posts about it separately.

Of course it's not as fast as my 5-year-old used Lenovo... But it's great for educational purposes (before anyone starts asking why you'd buy a bunch of Pis when one small laptop beats them performance-wise many times over).

I definitely get the educational appeal. Not just in construction and configuration. This should make a great platform for distributed computing development/testing/experimentation. What is the total build cost of a 6 unit system?

Hrm, if you'd clicked the Wiki in the top header of the link I gave you :) http://www.pidramble.com/wiki/hardware/pis

Curious. Why did you update to the Pi3 instead of the ODROID C2 + eMMC?

Mostly because of the community around the Pi. Interestingly, though, the ODROID C2 may be a much better option. I just don't know if I'll end up picking up more than one of them just yet.