I'm seeing it too....
Additionally, I just checked several domains of client sites that have .net versions which are 301ed, and they're showing the searched-for .net domain on the serp page. Mousing over the page title displayed in the serps shows the .net url in the browser status bar. Server header checks confirm that these are 301ed.
Searching a non-canonical variant on some domains will also display the non-canonical version, both in the url line and in the status bar on mouse-over.
This seems to be independent, btw, of whether the redirected domains had ever been previously promoted.
The behavior doesn't seem to be consistent with all domains that have non-canonical versions or alternate TLDs redirected.