If you can figure out which conference and/or tech session you may have seen the demo, there is a chance that you could find the recording at Esri Video | Videos Covering GIS Events, Products, People, & Topics
I did a search on arcgis.com (i.e. ArcGIS Online) and found a site on "where to move", http://www.arcgis.com/home/item.html?id=3942b8955e1b486a94ab9eb3268bb4b8 but it was having an issue loading all the layers. But you could use the layers of interest for you and build your own. Seems most of the "where to retire" are polls.
The "Data -Zillow Research" that Adrian mentioned seems to be summary info so you can look at treads over several decades, but no real current info. My guess is current data is somewhat proprietary since the Real Estate business is pretty competitive although seems like all the ads say they list all. Also, some sites seem to give incorrect locations on their maps, I think in an attempt to force consumers to use a real estate agent....my opinion only.
I found this site (although not sure that it is esri related) Home Prices and Real Estate Market Trends from Realtor.com
for what it's worth.