As reported by CNN (by way of Eurogamer), Apple is now valued at $500 billion - as much as the gross national product of countries such as Poland, Sweden, Saudi Arabia or Belgium. The company is also closing in on Microsoft, which was once valued at $600 billion (it's currently worth about $267 billion). Only three other companies have managed to surpass that milestone number: ExxonMobil, Cisco, and General Electric.
Apple's stock market value topped half a trillion dollars for the first time earlier today. CNN points out a handy chart of other things Apple is worth more than - found here.