Tomorrow’s the big day, but Facebook has just rolled out several minor changes that will also have an effect on Pages.

The most significant update focuses on Facebook Places Pages and how check-ins are calculated. In order to accurately reflect how many people have visited a location, Facebook will now count multiple visits during a 12 hour period as a single check-in.

Previously each check-in was added to your Page’s total. Additionally, if someone uploads a photo and tags several friends and the location, each person will be counted as a separate check-in. However, if someone uploads 20 photos from a location, Facebook will only count that as a single check-in.

This change is expected to go into effect over the next few weeks. You might notice a difference in your check-in tally.

The social network also made some improvements to comments, including permalinks and the ability to hide spam. Permalinks provide you with a direct link to any comment by clicking on its timestamp. While spam comments aren’t visible to your fans, they do appear sporting a darker grey background for admins. Now potential spam will be hidden behind an ellipsis.

And finally, Facebook has added a new “recently used apps” box on Timeline in an effort to give more prominence to Open Graph apps. But while this helps to make stories more visual, the new boxes take up additional space on your Timeline and pushes down other posts you’ve created.

Although these changes are minor, they will have an impact on how you measure your performance and interact with your fans.

[Via: Inside Facebook, Image credit: Alan Levine]