As you may know by now, Dr. Bussard passed away after losing a battle with cancer, but his reactor lives on. Continued development is now being done by a five member team calling itself EMC2 fusion, with a navy contract (the navy funded the original research).
The next in the series after the WB-6 (originally to be called the WB7) has been built, and in preliminary testing, it has produced energy in accordance with Dr. Bussards calculations. So far, everything is going according to plan. It has not been operated at the full design power levels yet however.
If this unit lives up to expectations, the next reactor built will be a commercial power level reactor. The advantage of Dr. Bussards polywell inertial electrostatic confinement design is that only electrons have to be magnetically confined, and because they have 1/2000th the mass of a proton, this is much easier to accomplish. It does not require superconductive coils or exotic materials as with a Tokamak and the machine is physically much smaller and about 1/1000th the cost.
Further, it can operate with aneutronic fuels such as Be-11/Hydrogen and in so doing eliminate the need for heavy shielding and the neutron activation that comes with neutron producing fuels such as deuterium-tritium used in most other approaches to fusion.
That WB6′s successor is so far living up to design specifications provides optimism that inexpensive clean and abundant fusion energy may soon be available to the world. The small physical size of the machine will make it suitable for some transportation applications such as ships, trains, and possibly even large aircraft.
The economics of the machine will make cheap unlimited fusion power available even to the poorest nations on Earth. This single technological development may completely revolutionize life on this planet.