I would caution you all against buying accessories for your Apple laptop now, a week before a major Apple announcement, but this external battery does look pretty handy. It plugs right into the MBP as if it were an outlet and gives (they say) 6-10 hours of extra battery life. Of course, my MBP is so borked that that would mean 6-10 hours of total battery life (thanks Apple), but hey.
Two caveats: one, you have to buy a new magsafe power adapter (or have yours modded) and two, the thing costs $450. Man, I could buy another laptop and just use that one when the first runs out!