Using your example, I searched for mail. The top 3 results (in order) were: 1 mail.com, 2 Yahoo! Mail, 3 GMail. Maps bring Google up first, but that's logical because they've spent so much money on their maps service. XMPP, brings up Wikipedia first, while Talk brings up talk.google.com first.
None of them show up in recommended, but at the same time, in the last case there are no competitors (that I'm aware of) so that isn't exactly anti-competitive. In the second case, that might be anti-competitive but IANAL.