While this is based upon info taken from people using Chitika's service, we've found overall trends are quite nicely tracked by this data. The latest report says that a full 15 percent of eligible iPhones, iPod touches and iPads are already running iOS 6. Considering it was released just yesterday? That's impressive.
As TechCrunch points out, after two months of Jelly Bean (the latest Android OS) availability, Google has seen an adoption rate of only 1.5%. Apple customers are a little quicker to react and install whenever a new iOS appears, it seems.
Of course, considering iOS 6 was Apple's first full version update over the air (5.0.1 saw the debut of OTA updates), adoption is likely that much faster as a result.