There could be a rational explanation for this. Those new to Windows Phone might be more familiar with using apps than with using People Hub. Another reason could be strong Facebook growth in China where Facebook integration is not offered and the app is the best way to access the social network. Growth has started to slow in early August, so more time will be needed to see if the surge in Facebook users is a real trend or just a fluke. It could indicate that buyers heard more about the platform during the Windows Phone 8 summit on June 20th. Another theory is that price cuts on many models is driving business. For example, the flagship Windows Phone model, the Nokia Lumia 900, recently had its price sliced in half by AT&T to $49.99 with a signed two-year pact.
Existing Windows Phone models will not be getting updated to Windows Phone 8 which should mean plenty of cheap handsets will be available as we move toward the end of the year. By then, we should have a better idea on what the July surge in Windows Phone 7 Facebook app users really means.
Growth in users of the Windows Phone Facebook app has slowed in August