Haesslich let us know that Nintendo will be releasing a special battery upgrade for its amazing new Gameboy Advance SP. The standard lithium ion battery current lets players play for 10 hours with the light on or 18 without. The uprated model will deliver about 18 hours of lit play and some 30 unlit. That's a lot of Prophecy time! It hits Japan next month for roughly $16. GamesIndustry.biz has an article on it here.