Ok, Eddie its compiling fine, and hasnt made any adverse effects or difference to my CEGUI-intensive app.
This is good news, since that was my main worry

So how exactly do I use it and take advantage of the new scaling functionality? Do I need to call a 'drawText' method directly, passing in the new paramaters to change the width and height scale of a font when rendered on a widget?
Yes, that's basically the current usage, or for direct-to-screen rendering as Debug is doing.
Once the functionality has been in a while I can imagine that there will be opportunities to extend the widgets to make use of the new ability. One thing I had in mind was a new "stretched" formatting option for text, whereby text would be scaled to fill the formatting area; but that's one for the future, I think.
In relation to your report about no adverse effects, I just finished up some profiling, and can report that while there is a very, very minor performance price, in the grand scheme of things this really adds up to zero.
At the moment I'm confident that the changes can be added to CVS without fear
CE.