You could use it to automatically get firmware and software updates. One likely way of doing it: use git to list out tags and branches, find most recent one with appropriate text in the name. Then check out the data from that revision, and use it. Maybe delete the local git stuff afterwards (since you don't need it any more). Or, better yet, archive the data from that revision.
You might not necessarily supply this solution as part of a product - but if you work somewhere that has a lot of devices to manage, you might want to do this kind of thing yourself, internally. And if you're going to then take it seriously, you'd want to keep previous revisions of all your stuff around, making it easy for you to roll back to previous versions. Files with history, and easy rolling back to previous revisions... git isn't the worst possible way of doing that.
(I've seen this sort of thing done with perforce, pretty much exactly as I describe, to deliver updates of internal tools and manage test builds of products. Daily builds of tools and products get checked in to perforce each day; most days, QA test that day's build results; if a a given day's build proves not to be a big pile of crap, they tag the corresponding revision. Then you can use perforce to find half-decent historical builds, and retrieve them. The place I saw this done at had a little tool that somebody had written to put a friendly GUI face on this process.)
Isn't this a problem that should be solved with a package management solution like yum or apt-get plus something for configuration management like puppet, chef or ansible? Git would still be useful, but only on the server side.
Possibly. I'm thinking more of retrieving an entire image, so you could also use FTP. Anyway, this isn't really my field of expertise, I'm just foolishly throwing out a random suggestion...
