The Office 365 Planner app is now available for U.S. Government Cloud tenants. Only it’s not the full Planner because some bits still have to be tested to make sure that they meet government standards.
Teams offers a number of ways to create new teams, which is good. However, if you create a new team with PowerShell, make sure that you add the team owners to the members list as otherwise they won’t be able to access Planner.
Microsoft has launched the preview of Google B2B Federation, which allows Google accounts to be used to access Azure AD apps. Quite how this will work out for apps that use guest user accounts is unknown at this point.