Hi Mathias,
For Mobile Kit Pro and mobile in general we are only targeting the major smart phones not all phones such as Nokia (We do support the newer Nokia Windows Phones but not other Nokia devices). For Mobile Kit Pro specifically we are targeting/supporting iPhone, Android Phones, and Windows Phones. We don't officially support Blackberry with Mobile Kit Pro because we have no test devices but we have been told it works and people can add blackberry to the user agent fragments config setting to make it use the Mobile Skin for Blackberry or maybe I will add it to the default setting even though we don't "officially" support it.
For tablets the main skin should be used and responsive design techniques can be used by designers to optimize it for tablets.
We have no need to detect more devices specifically since it is not a goal to support all devices but only the major smart phones iPhone, Android, Windows. Blackberry is having its last gasp of breath as it circles the drain in my opinion so there are really only 3 major smart phone platforms with a future, but even if you consider Blackberry as still a major smart phone platform it does work if added to the config setting. Beyond those 4 platforms is not a goal for us currently so we don't have need to detect them.
One still could add a user agent fragment for other platforms ie probably the word nokia could be added for non windows Nokia devices but if Mobile Kit Pro does not work well on those other devices it is not something we support so it isn't something we would try to fix or add special handling for, it would be a your mileage may vary kind of thing.
Best,
Joe