We will provide extended monitoring cababilities in Xpert.ivy Lauberhorn (5.1) were you can probe the current concurrent users over JMX. There will also be a Visual VM plugin for Xpert.ivy that displays nice charts.
For a preview have a look at the N&N of the Lauberhorn Sprint Release of the Xpert.ivy Server. You can download it on [ivyteam.ch][1]
[1]: http://www.ivyteam.chhttp://www.ivyteam.ch/flatpress/?page=dwnld