Microsoft has announced the new project called Microsoft Teams, a group chat workspace within Office 365. It runs on Windows, Mac, Android, and iOS.
Office 365 IT administrators can turn on Microsoft Teams by opening Office 365 Admin Center and selecting Settings > Services & Add Ins > Microsoft Teams.
More information can be found at teams.microsoft.com and techcommunity.microsoft.com/t5/Microsoft-Teams-Blog/bg-p/MicrosoftTeamsBlog
An overview of the Microsoft Teams developer platform can be found at msdn.microsoft.com/en-us/microsoft-teams/index.