The big news everyone is buzzing about this morning is that Facebook announced they are allowing people to check into locations. Similar to Foursquare.
Facebook said:
You have the option to share your location by "checking in" to that place and letting friends know where you are. You can easily see if any of your friends have also chosen to check in nearby.
It works on the latest iPhone app or on mobile HTML5 enabled browsers at http://touch.facebook.com/.
Facebook is using Bing maps for the place pages and Facebook is looking for advertisers for those pages.
This should make things interesting in the local space. Of course, there is Google Buzz which isn't used all that much.
Forum discussion at WebmasterWorld and Google Blogoscoped Forums.