I've been asked to support searching by email address in the Pownce API. This means that you could search for another Pownce user if you know their email address. Currently this doesn't exist anywhere on the Pownce website or API - search is by name or username only.
I'm fine with allowing people and bots to search by email if the email is "public" in the user's Pownce privacy settings. The problem is that by default your email is "friends-only" and very few people change it to "public".
To me there's also a difference between allowing another Pownce user to search for you by email address and allowing a bot to search by email address. Specifically, Google's social graph API plans search other social sites by email address to find your other accounts. This would be very helpful in helping you create profiles and find friends faster, but also could give Google a more of your personal data.
I suppose search engines could also do this by full name or username, but an email address is considered a unique identifier and lots of sites have you validate your email address after registering (though Pownce doesn't).
Flickr and Twitter allow searching by email address and Facebook actively tries to prevent it. What should Pownce do? Is Pownce obliged to try to protect user data that is flagged as private or friends-only? Does searching by personal data differ from displaying personal data? Comment below or on Pownce - I'll let you decide.
