AMT/IAI marketed the Hardballer Longslide (.45ACP) and Javalina (10mm) at one time. Both were identical with the only difference being the barrel, recoil spring, and magazine. I can't recall if the breachfaces of the slides are the same or not (making them caliber specific), I'll have to examine them when I get back up to my parents house some time. I do recall trying to swap slide assembles but the 10mm slide on the .45ACP frame needed minor slide rail fitting as it wouldn't fit all the way on. In any event, if you do have a 10mm barrel fitted to a previously .45ACP 1911, a much stronger recoil spring is necessary. The 10mm mags are the same as the .45ACP one but have internal ridges molded into the sides for the more narrow cartridge. IME, these are not really needed as I have been able to shoot 10mm using .45ACP mags.
Peters Stahl (Germany) still does make the 'Omega' line of 1911 based guns that are caliber interchangable with a simple barrel, recoil spring, mag swap. They, however, are not being imported into the USA (as far as I know). There are older Springfield Omegas out there when they were imported by them a long time ago. The entire slide assembly is very different from the regular 1911. It incorporates a linkless barrel system like today's SIGs, Glocks, HK USPs, etc. The flat breachface of the slide and dual extractors that self adjust to casehead diameter allow for the use of the same slide for all calibers. The dual extractor system isn't the greatest as empties will occasionally fly back at your face, at least in 10mm.