Yeah, I have OS/2 2.0, 2.1, and Warp 3 installed on my 486 PS/2. (I also have Warp 4, but it's CD-only, and the machine doesn't have a CD-ROM drive.) I also have PC-DOS 7 with Windows 3.11.

That's one of the nice things about OS/2, it handles multi-boot very nicely.