"It's interesting that you see how the App Store is doing when it was not that long ago -- about 2001 when the dotcom bubble burst-- that people were saying people would want information to be free on the Internet," Howe noted.

Even the recession has not held back this kind of impulse buying. "The recession doesn't seem to be having an impact. These small impulse purchases are kind of recession-proof," Howe said.

Rob Enderle, an analyst at the Enderle Group, said the two billion mark is "outstanding" given the number of phones available for downloads. Enderle said the application store concept might have come along earlier had bricks-and-mortar retailers not objected.

"The fact is, that with enough bandwidth, there's very little that can't be delivered over the Web," Enderle said. "We're witnessing what will probably be the end of the traditional software delivery model. App Store is an indicator that the times they are a changin'."