Wow, either Marcus Nelson, founder and CEO of social marketing startup Addvocate, doesn’t know that MySpace is attempting a grand reinvention, or he just doesn’t care. Talking about lost causes at MediaPost’s Social Media Insider Summit, on Friday, Nelson just asked attendees: “Anybody still on MySpace?!” Take that, Justin Timberlake! Beyond bashing MySpace, Nelson -- formerly head of social media at Salesforce.com -- was trying to make the point that brands shouldn’t leave “graveyards” around the Web, whether they be MySpace pages that haven’t been tended to in years, or microsites that haven't kept up with the times. “It’s ok if [a social media effort] doesn’t work,” Nelson said. But, if you’re ready to move on, don’t forget to remove those efforts by the roots, he warned.