Hey Maxim, I'm back with some news on the topic. Hope you don't mind I just "kudoed" you earlier instead of response.
So my further investigation showed AutoCAD isn't ready for Retina at all. I mean not only the UI isn't ready but model space too.
Here's a couple of screenshots in case you're curious. One capture shows AutoCAD 2013 for Mac running on a Retina display (screen resolution set to "scaled to look like 1680x1050", in fact screen is running in 2880x1800).
Another capture showing regular AutoCAD 2013 for Windows running on the Retina screen (resolution is 2880x1800, DPI set to 125%). Once you campare both images zoomed in you'll see the difference.