IMHO there are no such settings and they are not necessary. The current "friend" function is limited to displaying the changesets of "Friends" and their blog posts on the befriending users page. Both changesets and blog posts are fully public, so the current friend implementation does not encroach on your privacy at all, it is simply a convience function. ("friend" is a misnomer, it is more like "following" on twitter, where, very similar, your tweets are public anyway)

IMHO there are no such settings and they are not necessary. The current "friend" function is limited to displaying the changesets of "Friends" and their blog posts on the befriending users page. Both changesets and blog posts are fully public, so the current friend implementation does not encroach on your privacy at all, it is simply a convience function.