I don't recall this being built in, in 6.5. Though I could be wrong, I'm still hacking away on mine for my upgrade and haven't seen all the little features yet.
This could be done with a quick check against member groups on the showprofile page.
Myself, I code the email address right off the templates. Even though the displayed email address is supposed to be their "fake email" I don't want any addresses pulled of my site.
Learned that one the hard way, with the 30-50 spams a day I currently get.
I figure if folks want to contact one another they can use PMs.
I can probably whip up a bit of code to do this for you though, if you want to keep them there for certain member groups.