In an effort to simultaneously increase the growth of Facebook and applications, Facebook’s growth team tonight announced the launch of an update to the “multi-friend selector” to now allow app users to invite friends not already using Facebook to the application as well.

The new feature allows Facebook users to type in email addresses to send app invites to anyone. (However, it doesn’t provide in line access to contact list importing from popular email providers like Gmail, Yahoo, or Hotmail.)

Here’s how the user experience works:

When users type in addresses, a “special email” is sent which invites the recipient both to Facebook (where they will become friends with the sender) and to the application. When clicking on the email, the recipient is sent to an “Express Registration” page. After they join, the app from which the Facebook invite was sent will be bookmarked and present on the home page app menu.

At the end of the day, this update should help Facebook leverage applications to expand more deeply into demographic niches it has not yet reached. With over 50,000 applications on the Facebook Platform, that number could add up over the coming months and years.