Josh takes an-depth look at the navigation design implications of touch/keyboard hybrid devices, coming to a similar conclusion as Luke and Jason:
Unfortunately, the top-of-screen navigation and menus of traditional desktop layouts are outright hostile to hybrid ergonomics. Tried-and-true desktop conventions have to change to make room for fingers and thumbs.
Want to test for a hybrid device? Tough luck. Instead, argues Josh, the best you can do is assume that any device visiting your site could be touch-enabled.