Yes, it is.
Open up TortoiseHg Workbench on top of your repository.
Then click the Manifest button, it looks like this in the toolbar: 
In the list, find the file you want to look at, right-click and choose File History:
In the dialog that opens up, in the toolbar just above the file contents, click the button for the annotation view:
And then you should have your annotated view of the file. Note that a mouse-over on a line will show a status message at the very bottom of the window with the commit message and some details, but some details like single line changes with no content (ie. you added an empty line) might not give you a mouse-over. The revision number in the left column refers to an entry in the history list above the view though:
