Apple has released information [iTunes link] on the most popular App Store apps of all time, split down into free/paid and iPhone/iPad categories. The lists – published as Apple approaches ten billion downloads and offers a $10,000 iTunes gift card for the person who downloads the milestone app – reveal that Facebook is the most popular free iPhone app in both the US and UK, while Doodle Jump is the most popular paid iPhone app in the US and Angry Birds takes that top spot in the UK.
As for iPad apps, the top free app is Pandora in the US and Google Mobile in the UK, while the paid charts are topped by SoundHound in the US and TuneIn Radio in the UK. The difference primarily seems to be one of geographic availability: Pandora is not available outside of the US, for instance.
US Top Paid iPhone Apps
US Top Free iPhone Apps
US Top Paid iPad Apps
US Top Free iPad Apps