Its an interesting idea. If you're like me and don't really take very many gravity readings it would give you a much better idea of when the batch is done. I typically am very short on time at home so by the time I finally get around to checking in on my batches they are done but you never know, I might make time to check if I had geeky toy.
It really would come down to cost. If the cost is fairly low, quite a few geeks would pick one (or 5) up. If it is expensive than it becomes one of those things like a conical. It might be nice but those pesky kids seem to think they need food and school supplies, like every month!
The guys who are trying to build the completely automated brewery will demand you release an API with it so they can program it into the cyborg-brewer they are making.
All in all it could be a nice addition to the brewery.