I just pushed a patch (authored by Scott) to add .gitignore to the PS project so that fasls can be ignored. This is because, if you're using git submodules with PS, git thinks the library has changed every time you recompile it, unless you explicitly tell it to ignore fasls.
Git submodules aren't particularly simple, but we use them for one huge benefit: it lets git track which version of PS goes with which version of our code. So if we need to restore our system of a month ago, and there have been a bunch of patches to PS in the last month, git will check out the old version of PS that's contemporary with the old version of our stuff. This solves the huge headache of trying to run an old version of your code against newer versions of its libraries, which works until it doesn't and then is hard to track down.
I'd be interested if anyone has a better solution to this problem, because I'm not fond of git submodules, but am willing to live with them to get the above.
Daniel