ComScore has released a new list of the top 25 iPhone and iPod touch applications, based on estimates of the installed base of applications downloaded via iTunes by February 2009. The company, which says that it monitors roughly one million computer users in the United States, looks at its monitored iTunes users to determine which applications they had installed, and removes duplicates to avoid double- or triple-counting updated apps. According to the report, Tapulous’ Tap Tap Revenge is the top app, with 32% of monitored App Store users having downloaded the rhythm game. It is followed by Backgrounds, with 27%, Touch Hockey: FS5 with 26%, Facebook, also with 26%, and Pac-Man with 24%. Other notable entries in the top 25 include MySpace Mobile with 23%, Google Earth with 22%, Pandora with 21%, AIM with 19%, and Shazam with 17%. While the numbers strike us as unusually high for given apps, they provide a general sense of genre and app popularity. Overall, 12 of the top 25 apps are gaming titles, with entertainment apps accounting for four of the top 25, and three social networking apps making the list.