SharePoint 2013 will make applications available to SharePoint and Office 2013 via an application store. Similar to what you might be used to with your smart phone, you can Try and Buy Apps and also rate them as well as share them with your friends of colleagues. You can read about the background of Apps for SharePoint here: http://blogs.msdn.com/b/officeapps/archive/2012/07/23/introducing-apps-for-the-new-office-and-sharepoint.aspx
Nick Swan (MVP) at Lightning Tools is very proud to have an App already in the beta store. If you are trialing the SharePoint 2013 public beta, you can experience Social Squared by downloading it from the App Store. http://officepreview.microsoft.com/en-us/store/apps-for-sharepoint-FX102804987.aspx
Social Squared has been designed as a communication tool that helps build a community around your SharePoint sites. It looks, works and feels exactly how a discussion forum should be in SharePoint. Help your users move away from spending their life in email by discussing ideas and answering questions using an open forum tool.
More to follow soon!