Yup – It's a Farnsworth-Hisrch Fusor
http://en.wikipedia.org/wiki/Fusor 
and www.fusor.net
At first we were pretty skeptical of this home made fusion reactor instructable. However, we've seen home made fusion reactors before, so it is technically possible, we guess. The construction alone is interesting enough to warrant a few moments of looking.
We're not experts, so pardon us if we can't tell you exactly what is going on, but we can appreciate the craftsmanship involved with the build. The vacuum chamber specifically is quite nice.
Read more and comment at HackAday Homemade fusion reactor
My favorite comment:
Building a fusion reactor, especially from as poor-quality a writeup as Instructables provides, is like saying "Please irradiate me!" - Sad but true ;-)