The 'email' field in the profile is not visible to others (only seen by yc admin). 'About' is visible though.
edit: perhaps you could vote up and/or comment on rms' suggestion here: http://news.ycombinator.com/item?id=46100
Just like in a related way - but with a different morale - SMS seems from one point of view an inferior user interface. But people use it anyway instead of calling.
Anyway - I suspect he just has not come around to fixing it.