A feature that I did not see documented which would be an awesome addition is macro replacement within the header tags of the master page. I was surprised to see it in the editor and would be excited to see it rolled out as part of 4.0.

When you click on the ellipsis button to bring up the large text area editor in the master page tab the form now shows suggested macros.

However when we have tried to use these macros, we have found that no macro replacement occurs, and the raw macro itself comes through in the page results.

For example, adding the macro {%currentsite.sitename%} appearing in the page source, rather than the actual site name.