First comment on the post mentions Unison (http://www.cis.upenn.edu/~bcpierce/unison/index.html http://www.cis.upenn.edu/~bcpierce/unison/index.html), which I'd

First comment on the post mentions Unison (http://www.cis.upenn.edu/~bcpierce/unison/index.html http://www.cis.upenn.edu/~bcpierce/unison/index.html), which I'd never heard of - but looks pretty sweet for some things I've been meaning to do.