<p>Is it possible to to take a screenshot of a webpage with JavaScript and then submit that back to the server?</p>

<p>I'm not so concerned with browser security issues. etc. as the implementation would be for <a href="http://msdn.microsoft.com/en-us/library/ms536471(vs.85).aspx" rel="noreferrer">HTA</a>. But is it possible?</p>

You can achieve that using HTA and
VBScript
. Just call an external tool to do the screenshotting. I forgot what the name is, but on Windows Vista there is a tool to do screenshots. You don't even need an extra install for it.
As for as automatic - it totally depends on the tool you use. If it has an API, I am sure you can trigger the screenshot and saving process through a couple of Visual Basic calls without the user knowing that you did what you did.
Since you mentioned HTA, I am assuming you are on Windows and (probably) know your environment (e.g. OS and version) very well.