Is there a way to get the currently logged in users in Tridion? The system is non-SSO. Would an HttpModule be a viable option, or for example looking at IIS information about the Tridion Website? Any creative suggestions are welcome :).
There is currently no out of the box support for this. There are some Enhancement Requests related to this, but it's still unknown at this point when and whether they will be implemented. I will accept this answer so the question becomes closed. I will however update the answer once such functionality is available.