So what's TMG anyway?
Download details: Forefront™ codename "Stirling":
http://www.microsoft.com/downloads/details.aspx?FamilyID=65bd5f8a-d94c-457a-9f88-2046597130e1&DisplayLang=en
So if you want to see what TMG is all about..check out that beta (there's a Virtual one as well)
Read the complete post at http://msmvps.com/blogs/bradley/archive/2008/06/30/so-what-s-tmg-anyway.aspx