I've had one of these for a couple weeks now, and they're awesome. It's a 3rd party external battery that weighs about a pound that hooks directly into your Macbook Pro MagSafe. It also has a USB outlet for charging your iPhone or iPad.
They let me get a ton more mobile battery life on the go -- so no more running out of batteries on cross-country flights and/or at conferences without power outlets. On average I get 8 or 9 hours of charge with my 15 inch Macbook Pro Unibody (circa 2009).
Not sure whether I should be angry at HyperMac for not properly licensing the power connector or Apple for refusing to license it.
This is a shame. But apparently they're being sold for the next two weeks before getting discontinued. If you've ever had problems running out of juice on the go, I recommend picking one up.