In order to use the cmdlet first you'll have to grab the Microsoft Visualization Components from Microsoft Research.
If you don't want all the visualization components here is a zip file of just the treemap generator dll. Unzip it and put TreemapGenerator.DLL in your scripts folder.
Grab this file to get the scripts I demoed at the meeting.
Let me know if you have any questions or comments.
I'm hoping to do a full writeup for the blog soon.
Edit 1/10/2012: Clearly I never got around to writing a full blog post. I was going to post a screenshot or two but I have found that the treemap generator does not appear to run under Windows 7 64-bit. When I try to run it I get the error:
New-Object : Exception calling ".ctor" with "0" argument(s): "Could not load type 'Microsoft.Research.CommunityTechnologies.Treemap.NodeColor' from assembly 'TreemapGenerator, Version=188.8.131.52, Culture=neutral, PublicKeyToken=3f6121a52ebf7c82' because it contains an object field at offset 0 that is incorrectly aligned or overlapped by a non-object field."
Maybe someday I'll try to resolve this for Win7 but don't hold your breath.