Ooooooo interesting, Drago!
So, using Get-CsWindowsService with the appropriate services, you should be able to see the connected users and active conferences.
The trick is you'd need to run this for each individual computer in your pool, if you have a three server front end pool, you might want to script it to tally it up for you, if you have one server then you just run the commands as is:
#Get total number of active Web Conferences
Get-CsWindowsService -Name RTCDATAMCU -ComputerName YOURFRONTENDSERVER
#Get total number of active screen sharing conferences
# watch for (connected users)
Get-CsWindowsService -Name RTCASMCU -ComputerName YOURFRONTENDSERVER
#Get total number of Audio\Video conferences
# watch for (connected users)
Get-CsWindowsService -Name RTCAVMCU -ComputerName YOURFRONTENDSERVER