Thanks for the reply(ies). That did the trick. As it turns out, it looks like the earlier versions just placed that tag in the default.aspx. The current version conditionally injects it as in the code snippet above. Now, according to robottxt.org 'Index, Follow' is the default so having dnn injecting it for all pages just makes turning that off at the page level unneccessarily tricky. There is no telling how a bot is going to behave if conflicting tags are present.

Thank you Rob.

What if the code was something like (disclaimer, I'm not a programmer):

If Request.QueryString("deindex") IsNot Nothing OrElse _
 If Request.QueryString("ctl") IsNot Nothing AndAlso _ 
  (Request.QueryString("ctl") = "Login" OrElse Request.QueryString("ctl") = "Register") Then
  MetaRobots.Content = "NOINDEX, NOFOLLOW"
Else
  MetaRobots.Content = "INDEX, FOLLOW"
End If

Then all the tabs, modules and controls would have to do is add the deindex variable to the query string.

Or perhaps even better would be...

If Request.QueryString("deindex") IsNot Nothing Then
  MetaRobots.Content = "NOINDEX, NOFOLLOW"
Else
  MetaRobots.Content = "INDEX, FOLLOW"
End If

and change the login and register controls to add the variable.