Masochist that I am, I wanted to edit a question to include some code that had been added as a comment... from my iPhone running iOS 5. Unfortunately, the comment text is not selectable, either in the mobile version or full site version. Why not?
If I touch any comment, the grey box runs from the top of the first comment all the way down to the bottom of the add comment box. Selection from elsewhere is fine.
If I am not logged in, comment text is selectable. And, as noticed by Arjan, you can't flag comments from the mobile version of the site either.