According the the Facebook Developers blog, Facebook is now granting developers on Platform the ability to request (or require) users to hand over their email addresses. By doing so, developers can begin sending periodic messages directly to users.
This actually doesn’t come as a surprise: Facebook initially talked about e-mail requirements last October and has kept developers updated on the timing in its Developer Roadmap. All of that said, this is a big deal!
Up until now, Facebook applications have used the notifications window (that slide up panel in the bottom right hand side of the screen) to engage users on an ongoing basis. Facebook is removing that functionality in the next thirty days. Moving forward, Facebook will no longer be the gatekeeper for communications between developers and users.
In order to collect Email addresses, Facebook developers will prompt users through an extended permission box. For those concerned with potential spam, they can elect to only share a proxied Email address – similar to the ones you can get when posting items on Craigslist.