I am sure I heard a Pro Triathlete using one. Maybe a female, but I cant remember. They always good get write ups. I personally am not a big fan becuase of the simple reason that Focus reminds me of the name Ford Focus, and they are not exactly great cars.
Correct me if Im wrong but doesn't Stuart Hayes ride a focus, i think he races on an Izalco extreme.
Do bear in mind that a sponsored rider may ride a particular brand of bike, but under the skin it is a different bike than what the badges/decals say..