Oh, I didn't notice the "unsupported" part. Mine says that, too, though. Interestingly enough, I *don't* see it on my laptop or a Debian server here at work. On the Debian server, it's 1.12, and it comes straight from Docker themselves. On my laptop, it comes from the Arch Linux community package, which compiles the docker binary instead of downloading a pre-built binary from Docker. So, I guess my initial theory that binaries that *don't* come straight from Docker themselves have that "unsupported" bit is false. I also don't see it on my personal Debian server, where I installed Docker 1.6.2 from the Debian repository, so it's not phoning home and asking if it's still supported.
So, no idea why it says that. Sorry.