It's a hard job porting CAD software to other operating systems. Indeed, the hardest job is the very first task. The CAD vendor needs to decide which way to go:
#1. Give CAD software a uniform look on all operating systems.
#2. Make the CAD software look like the operating system.
There is no "And."
When Bricsys ported Bricscad to Linux and Mac, they decided on #1. The result is that they had to custom-code a lot of stuff for Linux and Mac that's native on Windows. It's hard work for the vendors, but users benefit from running software that looks the same, something that's a significant advantage to multi-OS design offices.
When Autodesk ported AutoCAD to Mac, they decided on #2. The result is that they can ignore large swaths of Windows-specific stuff, because Mac users wouldn't expect it. The drawback is that much more code code must be rewritten, and so the first release of Acad/Mac had just 2/3 of the commands found in Windows, yet sells for the Windows price. The benefit is for Mac-only users who face software that runs the way they expect it to; multi-OS offices are not so well off.
Anyhow, back to the title of this posting. Bricsys has been (unhappily) forecasting the immanent release of Bricscad for Mac in "a couple of quarters" for a few years now. Some 2.5 years ago I reported Bricsys saying that "once Linux is out the door [in 2010], then it's the turn of Macintosh." A year and a half ago, Henrik Vallgren reported that "once the Linux version is released, expect a quick path to Mac OS X."
Now, an insider tells me the Mac software will enter alpha testing this Spring, and the company's own press release of Monday said to expect "the entire Bricscad V12 suite on Mac OS X in the second half of 2012."
No matter a CAD vendor takes route #1 or #2, it's a long haul to port CAD to Mac.