Lightroom writes out all your metadata for a given image into the xmp "sidecar" files. I regularly copy pictures to my laptop, process them in Lightroom, then copy the raw files + xmp files over to my desktop, and everything just works.

What doesn't just magically work is when you start making "virtual copies" of your pictures. Do that, and you're guaranteed a world of hell in trying to move your images from one computer to another.

Picasa, last I checked, has its own proprietary but remarkably simple text format, one file per directory, where it writes everything out. Not really a big deal to write a short Perl/Python/whatever program to crack it.

I have no idea about ACDSee.