Actually that sounds like a good idea. The ability to monitor an ingroup (even if it's just a simple list of agents logged into it, not actual live calls ... although I'm sure that would follow) sounds like a reasonable request. Considering that's what we have in Asterisk by monitoring "Queues" (members and calls waiting).
And all the information is available in appropriate tables, just not in a single screen dedicated to the purpose.
I'm not sure about putting it directly into the real time screen right now ... but certainly on a simple report screen would not be entirely difficult. I will say that if a report were created for this purpose, its viewpoint would be skewed enough that it may never be combined with RealTime. For instance: on later, more sophisticated versions, it would be a good feature to show summary and drill down data and show users who have permission to log in to a specific ingroup, and are logged in, but are not actually IN the ingroup (taking into account the campaign they are logged in to, and other permissions). Showing them "greyed out" but visible, and having a button to "just log them into this ingroup" directly from the interface. (So that agent avoiding the high-volume ingroup can just be logged into it without a great effort.)
Find the appropriate tables in the database for live calls and generate a quick mysql report!