This is a familiar request that was partially prompted by this Tridion StackExchange question:
https://tridion.stackexchange.com/questions/19166/tridion-list-of-currently-logged-in-users
We'll leave this under community review for a while to solicit ideas and feedback. In the meantime, use cases and examples are definitely appreciated, specifically focused on what an administrator would be interested in knowing about the system and why.
If it makes sense we might pull out specific parts of this idea to have a bit of granularity in case we implement or otherwise enable parts of the idea.