Hi Libra,
Seems to depend on the browser. Internet Explorer 7 for Windows seems to just show you today's date when you right-click and select properties.
When I did this for heritagecapitalcreditcorp.com, it showed today's date as date modified.
However, when I right-click within Firefox for Mac (yes, it's possible to right-click on a Mac), it showed March 28 as the last time the page was updated. I'd have to look more into the intricacies of the browsers, but I wouldn't trust what IE 7 tells you as the "date modified" - especially if it shows today's date. Of course, if you notice changes on a daily basis, then today's date is fine, but since my Mac is showing March 28 as the last date changed (and frankly, I think that is about right given the fact that I look at HCPC's site every day and it doesn't look any different), I wouldn't rely upon right-clicking and viewing properties as a definitive way to know if the web site has been updated.
Honestly, I think we'll know when they update their web site with anything significant. They'll make it apparent, I'm sure :).