I don't think this is true. I know a few people who are on facebook and use the same email address on facebook that I have them down as in my phone, and facebook mobile did nothing with their numbers (which they have not put up there).
Facebook had my number because you end up giving it when you try use the official mobile apps, and they add it to your profile at that point (which makes it available to all your contacts if you are not careful about your privacy settings). Are you sure that it doesn't have the numbers of people in your phonebook either because they explicitly added it to their profile or because they have used facebook's "mobile" options?
(unless of course this is something new: I've not touched the mobile apps for mobile version of the site as accessed via browser for some time, as to my knowledge none of them support the use of HTTPS instead of plain HTTP yet)
"When you download Facebook’s mobile app, this feature syncs your phone’s address book with your profile. From then on you can access all of the numbers in your phone from your Facebook profile."
Facebook had my number because you end up giving it when you try use the official mobile apps, and they add it to your profile at that point (which makes it available to all your contacts if you are not careful about your privacy settings). Are you sure that it doesn't have the numbers of people in your phonebook either because they explicitly added it to their profile or because they have used facebook's "mobile" options?
(unless of course this is something new: I've not touched the mobile apps for mobile version of the site as accessed via browser for some time, as to my knowledge none of them support the use of HTTPS instead of plain HTTP yet)