URL shorteners, like bit.ly, have become a popular way for people to share links on Twitter while taking up as few of the allotted 140 characters as possible. But saving space is just one of the benefits that shorteners provide. Others include getting traffic analytics like how many people are sharing links from which sites. So it’s especially interesting that Facebook is rolling out what appears to be its own URL shortening service, called fb.me.

A URL shortener makes increasing sense as a Facebook feature, because the site is trying to be more open and connected to other web sites and Internet-connected devices.

Facebook recently began automatically shortening URLs that appear in its mobile interface. So, instead of text link to a Facebook photo appear as http://m.facebook.com/photo.php?pid=35877484&id=1310743&l=a373e8038d, you might see it see as http://fb.me/3Bkj7CW, as Polaris Ventures’ Ryan Spoon noticed (see his screenshot, below).

Fb.me also works as a substitute for any other Facebook page. So if you can write http://fb.me/starbucks instead of http://www.facebook.com/starbucks, as blogger Saad Kamal points out, meaning brands with Pages can more easily do things like share links to Facebook on Twitter.

Facebook has spent the last year improving mobile access to its services through its own mobile web site and device-specific apps as well as through tools for developers, carriers and device-makers to build their own apps and services. A shortened URL makes especially good sense here. In the screenshot, showing Facebook text alerts, you can clearly see that the shortened URL provides a simpler, easier to read user interface.

The company has made Facebook Connect a focus this past year, introducing ways for people to sign in to other sites using their Facebook identities and share information back and forth between those sites and Facebook. It has also been pushing users to be more open, most recently changing its privacy settings to get people to make content they share on Facebook also available on the web. It’s possible that the company will make fb.me the default for any content that users share publicly, in the hopes that the shortened URLs make for easier re-sharing.

It would also not be surprising to see Facebook provide analytics around shortened URLs, especially for Page content so Page owners can track web-wide sharing. Other increasingly common shortened URL features, like customizing the URL ending, would also make sense — especially given the option Facebook introduced earlier this year to let users and Page owners create their own vanity URLs.