@fBoyle-- I have facial dandruff as well. The technical term for it is seborrheic dermatitis, which is what scalp dandruff is.
As far as I know, it's caused by excessive oil and yeast. Yeast loves oil, it feeds on it, so if you wash your face frequently, it will help. At least once a day, take some boiled water and put a little bit of baby shampoo in it. Then, take a washcloth, soak it in the hot water, put it on your face and wipe your face with it. This will not only remove oil, but it will also kill yeast, fungi, etc.
There are also prescription or over-the-counter topical creams that can be used. Ask your doctor about it if you don't see an improvement soon.