Bing announced the release of a new Windows Phone app today, called “Wer’e In”. It’s basically a way to plan get-togethers with friends.

“We’re In makes organizing get- together’s, carpooling and trying to find people in a crowd a breeze,” says Bing in the announcement. “Any time you want to see where your friends are—We’re In can help you. It’s simple, invite your friends, and when they join, they’ll see your location and you’ll see theirs. When the invite expires, so does the shared location – no complicated process to worry about.”

“We’re In is a great way to save time and frustration when planning your roadtrip or meeting your friend at the mall – helping you connect with your friend faster,” Bing adds.

The user picks their friends from the contact list, or enters their phone number, and says what the event is. Users can also specify how long they want to share location info. Then the friends receive text messages with the details. The friends can use the app fi they have it or they can join using the mobile site.

Friends’ locations appear on a map once they elect to join. I guess this is so you can track them until they get to the place you’re meeting.

Further messages can be added in case plans change or somebody’s running late.

While it’s only a Windows Phone app at first, the company says it will be bringing it to more devices.