Depending on what I'm doing. Draftsight(Dasault systems) has a CAD version for Mac. Eclipse IDE works on the Mac and with some elbow grease the GCC compilers work under Mac, which is what I'm doing some of my embedded programming under mac with. Microchip also has an IDE that works with Mac, but sadly some of the other chip vendors still need to find a way to make it work. For the rest of it, definitely a VM to use Altium Designer for board layout and verification(gEDA tools aren't quite there for me yet, although they work on the Mac also). Alterra and Xilinx are definitely under the VM for the CPLD/FPGA work. So we're definitely out there, and we're slowly taking back the market to a system that runs more stable than, error, stop, restart, do over...
I couldn't use a Mac, because there's no software support for many of my needed tools. There's more support for Linux than for Mac; for example, Ixxat and Kvaser have Linux CAN drivers, but no Mac drivers.
Besides, I don't want a Mac beause I think different (from Jobs or Ives): Apple simply doesn't make any systems that fit my needs, and I won't pay a lot extra or accept compromises just to get a fruity logo.
Another Linux datapoint: my brother has been using Linux for >15 years for embedded software development, PCB design, research, and testing.
Virtualization can be a brilliant way to handle long-term support: Your 15yr old OS, application software, and user files can all live in one big image file as you mention. A double-click, and the entire environment is fired up, even though your current OS & HW are four generations removed.
Whenever we can we prefer OSX and the Mac for engineering software. One tool I couldn't live without is IGOR from Wavemetrics. No, this isn't an ad, I have no connection to Wavemetrics. But I have been using their software for more years than I can remember. Probably version 2 circa 1990.
Hear say hear say: I fully agree. We threw out our Windoze-PC's about 6 years ago and are very very happy. Even under emulation (Parallels) my CAD tools work great (under Windoze eXperimental Package) and the rest we do is pure MAC. In time it saved us lot of engineering time. Windoze just is 1 file to backup to our RATE harddrive. We love it and hope this will stays this way upto my pension age ;-)
Might be a case of people finally getting thoroughly fed up with Windows, which happened to me 16yrs ago! :-) Might also be the iOS halo effect. Or maybe more and more developers are finally coming to their senses and realizing that multiplatform is the way to go.
Any vendor that goes multiplatform definitely gets my interest. Microchip's IDE is a good recent example. Most software on the hobby end of the spectrum (e.g., Arduino) is multiplatform.
I find it interesting that a great majority of demos I've seen (images, videos) of multiplatform SW use a Mac :-) And, there's a fair bit of open-source SW that only has Mac & Unix/Linux versions (OS X being Unix of course).