When Autodesk began introducing Autodesk 360 based tools and services they provided us with a place to sign in to our account within Revit too. We can sign in via the Info Bar.
Regarding using worksets, when we are using Revit 2014 we can sign in to our A360 account and it leaves our current Revit username alone. When we are using Revit 2015 logging into A360 will attempt to change our username to match our A360 username. If we are already working in a Local File with a different username we'll get this warning message and signing in to A360 fails.
If we are working on a project that doesn't use Worksets we will be able to sign into A360 but it will change our username in the process.
If we attempt to open an existing Local File later we'll encounter this warning.
If we intend to work on a project, that uses worksets (as many of us do), then we need to make sure we've already logged into A360 before we create/open our Local File to avoid this issue. In Revit 2015 we can sign into A360 via the Options Dialog too.
I'm making a habit of checking my username before starting any work AND logging into A360 first if I intend to use it. That's the tricky part, will I and when? How many people this affects right now compared is another question. The concept of Autodesk 360 poses EyeTee with an interesting problem, creating and managing separate user (other than their own domain) accounts at Autodesk.