faceb.png Facebook will introduce significant changes to its developer platform in the coming weeks, according to a post this evening by Facebook’s senior platform manager, Dave Morin.

He says the goal is to build Facebook users’ trust in third party applications on the site, so the best apps win and growth happens naturally, not spammily.

While we’re short on the specifics at this time, here’s what to expect:

News feeds will become a better viral app distributor: Each Facebook user’s homepage features “news feeds” that show you the most interesting actions your friends take on the site — such as posting hot pictures of themselves, or talking trash to each other.

While news feeds already show you when friends add a new application, Facebook will start optimizing news feed algorithms to better highlight popular applications to friends who haven’t already added them.

Even though Morin says news feed changes won’t come right way, we already know that proper tweaking of the news feed algorithms could ensure a perpetual viral channel for the best applications to keep getting exposure.

Bad apps will continue to get busted: Say goodbye to spammy invites to apps, spammy email notifications, and spammy app content on your own profile — hopefully.

Facebook will revamp how users are able to manually invite their friends to install a new application, introducing a variety of options for developers depending on the type of app they build. When Facebook first launched, you could invite as many friends to applications as you wanted. The company quickly limited how many invites you could send per day, per app, because of rampant tricks by some app developers to get people to unintentionally invite friends.

Users will, at least for now, say goodbye completely to annoying email notifications sent from applications; Facebook may re-introduce email notifications, once it figures out how to spare users the spam.

As announced last week, Facebook is also restricting applications from displaying content within your profile page that you haven’t been told about.

Better metrics for app junkies: Users and app developers (and the reporters who cover Facebook) will get a better measure of which apps people care about enough to use on a regular basis, rather than how many total users have each app installed.

This move isn’t surprising, as Facebook itself makes a point of announcing its “active users” — people who logged in within the last month — to highlight how its competitors have trouble keeping their own users’ attention.

This metric should also help fledgeling ad networks on Facebook see which apps get the most recurring eyeballs — and have the potential to bring in the most ad money.