Some interesting stats from Shyhook Wireless over at O’Reillys:

According to Skyhook Wireless over 300 iPhone apps are location-aware as of October 3rd. According to Mobclix there are over 4,000 apps in circulation. If these numbers are correct this puts the location-aware percentage at under 10% — far, far less than I would have suspected based on my own experience.

Popularity: 11% [?]