There was in fact a PPC version of OS/2 Warp released for the IBM Personal Power series desktops, models 830 and 850, and ThinkPads 820 and 850. It was an extremely low key release (especially after expectations, but IBM took so long in development, the market had dried up) and was never actively marketed. It shipped on a few systems though, that were available to the public, so in theory, a CD or two might exist . . . I've seen a beta version once, but never a release version. If you happen to come across it, good luck finding a machine it will install on and drivers for, well, virtually anything. It is interesting to note that this beta version I saw had full PC-DOS 7 support (through x86 emulation, of course), and even ran Win-OS/2 programs full screen or in a window, on the PPC platform, although full TCP/IP stack support was never implemented.
NT 4 for PPC is real, and I, in fact, own a copy . . . somewhere . . .
Microsoft quietly dropped support for it after Service Pack 2. Of course, iMac600 is correct: there is absolutely no hope of support with the Mac firmware. For the masochists among us, it is possible Open Firmware could be coerced into booting off of a specified non-Mac partition containing an NT installation, perhaps using a piece of Open Firmware interface software (I remember something like this was available for LinuxPPC distros, but I can't find a link now). Then, even if you got that, you'd run into a lack of support in NT's HAL (Hardware Abstraction Layer), which would be a problem even with native PPC virtualization software. Windows NT requires much, MUCH more than do the Mac OS and UNIX beasts in terms of hardware support. Merely being compiled for the right chip gets you about 25% of the way.
Indeed, your best bet is to go with emulation. Contrary to reports by Microsoft and other skeptics, all versions of NT run beautifully emulated on a Power Macintosh.