How much content do community sites "own"?

GeoCities home page builders are finding that before they can enter the new Yahoo-GeoCities site, which launched recently, they have to agree to new terms of service--including one that some equate to signing away the rights to their intellectual property. The term in question gives Yahoo "the royalty-free, perpetual, irrevocable, nonexclusive and fully sublicensable right and license to use, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, perform, and display such content (in whole or part) worldwide and/or to incorporate it in other works in any form, media, or technology now known or later developed." "Now with the merger [between Yahoo and GeoCities], my Web site is no longer my own intellectual property, and the blood, sweat, and tears I put into it is now worthless," Adrean Clark, a GeoCities user, wrote in an email to CNET News.com. "If they ever decide to use any of my graphics or personal writings, they can sell it for their own profit."