I thought this was around for a while. I guess they just finally got some time to have a blog post on it.
However, it doesn't (didn't?) email you when you change your email address. So if you want to silently add a public key, you can temporarily change the email address, add the key, and then change the email back. Of course it's not a huge concern, since you need the password anyway, but it just makes relying on this email alert slightly less reliable.
Apologies if this has been changed/fixed already. I haven't tested it recently.