While going through the Mobile Tools issue queue today, I noticed some questions on the device detection mechanism in Mobile Tools and how some desktop browsers are wrongly detected as mobile devices.
To be honest I don't use the Mobile Tools built in device detection mechanism myself.... The simple reason is that Mobile Tools has a set of rules that try to discover the nature of the accessing device by looking at the user agent string. Have a quick look at the code (line 496: function _mobile_tools_is_mobile_device()) to see how the device detection works.
You will understand that the effort in keeping up with new devices and browsers is not an easy task, and these rules become inaccurate or outdated. It is sufficient and recommended for testing and quick prototyping during mobile development... But I would not recommend using it for production sites!