The obvious evolution of this would be to host email and allow users to forward:<p><pre><code> username@github.io -> useremail
</code></pre>
The fake non-routable emails can be a problem when you have to get in touch with contributors who are no longer active on Github.<p>Saw this problem in the bootstrap project where we still can't get in touch with ~10% of users to get them to approve the addition of an MIT license:<p><a href="https://github.com/twbs/bootstrap/issues/2054" rel="nofollow">https://github.com/twbs/bootstrap/issues/2054</a>
Anyone seriously worried about privacy should also ensure that their gravatar doesn't point to their real email address, especially if there's a simple relationship between the email addresss and GitHub username.<p>Edit: Apparently, this doesn't re-write the actual repo so anyone seriously interested in e-mail addresses will be unaffected. It was already easier to get e-mails via cloning rather than through scraping or the API.
This seems kind of like privacy theatre to me. What's to stop someone from just cloning your repos and deriving your email from the commit attributes?