Hey Paul,
Good point. I think the term white pizza can mean quite a few things, but there is definitely an Italian pizza called Pizza Bianca. It's roots can be traced back to Rome, and it is a long pizza made with olive oil and salt (and perhaps some Rosemary). The pizza is a meter long, and sliced, weighed and sold by the piece. It it is similar to the Tuscan schiaciatta. Emphasis on the good olive oil.
Here is a link to Campo de Fiori in Rome. I've never eaten there, but know folks who have said their Pizza Bianca is perfect. They even teach restaurants outside of Italy how to make Pizza Bianca.
Forno Campo Dé Fiori - Home Page
Check out the meter long pizza peel.
James