If you are curious to know what brand of mobile phones are popular among your site visitors, check out PercentMobile - it’s something like Google Analytics but for mobile devices.
With Percent Mobile, you get to know the exact cell phone models that people are using to read your website along with the most popular screen sizes and the geographic location / ISP of mobile visitors- see sample report.
PercentMobile is in private beta but you may signup using the TechCrunch code - freecoffee - for instant access.