A couple weeks ago, Facebook quietly introduced a new page to its developer site, listing all of the ad networks that it has approved for developers to use in applications — meaning those that have signed on to the ad provider platform terms.

The page, and a company developer blog post published last Friday, state that all developers can only choose ad providers from this list. Providers who are not listed cannot be used.

A list of ad providers existed for years in the now-removed developer wiki, but Facebook didn’t require developers to only pick from the list. But it introduced a new set of terms for ad providers, including offer companies, in early 2010, after it faced intense criticism over companies on the platform that committed abuses like tricking users into taking scammy offers, or reselling user data to outside companies. It has been updating the terms throughout the year to give itself more flexibility enforcing against illegal and anti-user practices.

Since the new listings page went live, Facebook has been steadily adding more companies. Google and its Adsense network for web sites is missing, as Outblaze chief technology officer Yusuf Goolamabbas noted after first discovering the page — the reason, we suspect, could be simply that Google hasn’t signed the terms. Other long-time providers Adknowledge (owner of Cubics and Super Rewards) and Tapjoy (formerly Offerpal) were only added in the last few days.

Given that large providers are only just now coming on, it’s not clear when Facebook is planning on any major enforcement.

Here’s the current full list. We’ll be covering additional changes as we see them.