I had the following conversation:
Him>
I can't figure out how to hide my e-mail address from the profile page: https://sourceforge.net/u/USERNAME/profile/
Me>
I don't see your email address there. That is, you only
see your own. See https://sourceforge.net/u/rbowen/profile/ for example.
I see my address there, you don't.
Him>
Ahh. Probably a good idea to make that more obvious, then.
Here are the reasons I came to that mistaken conclusion:
It looks no different than any of the information that IS public.
It seems to have no purpose but public display (eg. It's in a public profile page and it has no link to the relevant settings page, which might help to indicate that it's intended as a convenience shortcut)
The fact that it shows gravatars next to them further reinforces the impression that it's meant to be for public display.
There's no obvious option to turn it off, which can make someone who's already drawn the previous conclusions more emotionally agitated if they DO want to ensure nobody sees their e-mail address in the clear.