There's alot of changes happening over at Facebook, none of them being particularly small either. Beginning today, Facebook Applications can ask for (or demand) your email address so you can use their application, and they can send periodic updates or notifications to your email address. According to Techcrunch it's not out of the blue either, with the company announcing this last October, as well as keeping dates on the Developer Roadmap too.
The little notification window on the bottom right of the screen that you're so used to getting friendly updates from is being removed in the next 30 days, as part of the latest Facebook revamp and was the only way Facebook Applications could communicate with users to keep them interested in their application. Now, developers will not be able to rely on Facebook to "serve as the gatekeeper for their communication with users" and they will need to find alternative methods. This is not necessarily a good move for all developers.
When an application sends a message to a user using Facebook's notification box, it's pretty hard to miss - it gets that bright red little bubble, and your last few messages are shown if you click on the icon. Techcrunch goes on to point out that with Email, users may miss or forget that the application has notified them and the email will get lost in the mess (or the user will just get generally annoyed with the emails). There is a plus side though, application developers will now be able to send as many messages as they like to users via Email.(Facebooks notification system has messaging quotas) This move could be terrible news for applications that send out millions of notifications.
To get their hands on your email address, developers must prompt users through an extended permission box - not dissimilar to what you usually see for other requests. They can also request this information as part of the application installation (in other words, you may not be able to use some applications without giving out your email address. Techcrunch also points out that Facebook users who are worried about spam can elect to share a proxied Email address.