On the same machine? Yup. At the same time .... well, with caveats ... performance being foremost.
You can make a dual-boot disk, and have your machine boot windows, or have it boot Mac. There are companies working that will allow the Mac (spelled 'Linux') OS to run Windows software programs, so your OS will be Mac, but your programs you have purchased will run on the new Apple OS.
There is only 1 catch that I'm aware of. Apple has enjoyed a non-competitive stance against pirates because you just can't find PowerPC motherboards and PowerPC chips out in the wild. However, you can find BILLIONS of x86 motherboards and processors. A forsee a plethora of Mac 'clones' running the MacOS on non-Apple motherboard designs. The hackers are at work already on defeating the security measures Apple is building into their x86 OS X release.
Try (spelled "BSDFree UNIX") instead of "Linux"...