So what's their secret? It's a high quality game, first of all, and PopCap has a reputation for making those already. Second, the game itself had a fairly high profile even before release, since it was extremely successful on the PC as well. And finally, you have to think that the price figures in as well -- I thought the game would sell for PopCap's usual $5, but they actually sold it two dollars less than that. They'd probably have still made a lot of money, but I don't know if they'd be talking about 300,000 sales at a price just two dollars higher.
Then again, the game is already available for free online, so maybe the quality and PopCap's profile played a bigger part than the price did (they also trumpet the fact that Bejeweled 2 is also one of the top five grossing apps on the App Store). Congrats to PopCap on all their success. Oh, and our free time called, too. It surrenders.