ArcGIS Portal

ArcGIS Portal is the application and technology behind ArcGIS.com. ArcGIS Portal is the locally installable version of ArcGIS.com. Customers who look to leverage ArcGIS Portal are typically on secured networks or locked down to an intranet.

Release Information
In the early pre-releases implementations of Portal you can find out the vintage of the software by entering the following into a browser.

http://domain.com/home/builddate.txt