Sony's announced that online battles between friends will be coming to SingStar in June. That's right, they weren't already there.
Before the feature goes live, Sony will need to beta test it. If you'd like to help, fill out a questionnaire and await Sony's response.
Online Battles require sending an invite to a friend who must also own the song you intend to sing. You'll be able to use your PlayStation Eye to see what they're up to and also view their score, live.