I would like to thank everyone who provided input on this topic. It certainly helps when considering where to go. One conclusion from this is that we should get Peter's MSVC support finished and completed for Automake 1.12 and the next Libtool release.
I wasn't aware that there are more MSVC-related build system tools which one could target. I'm still not sure whether the idea to produce support for some of them should be buried completely, but I for one won't be pursuing it in the nearer future. If somebody else feels scratching that it however ... And of course I would be delighted if some of you provided fixes for pkg-config and whetever else is needed to make building for this setup work better. Thanks, Ralf