This from James Wakefield over at Focus-Online:

7 July 1999: As a result of the combined efforts of thousands of people willing to make themselves heard, Yahoo has just altered the Geocities Terms of Service to guarantee that your work will only be used for the purposes of "displaying, distributing and promoting your Yahoo GeoCities Site"

"7. CONTENT SUBMITTED TO YAHOO GEOCITIES Yahoo does not claim ownership of the Content you place on your Yahoo GeoCities Site. By submitting Content to Yahoo for inclusion on your Yahoo GeoCities Site, you grant Yahoo the world-wide, royalty-free, and non-exclusive license to reproduce, modify, adapt and publish the Content solely for the purpose of displaying, distributing and promoting your Yahoo GeoCities Site on Yahoo's Internet properties. This license exists only for as long as you continue to be a Yahoo GeoCities homesteader and shall be terminated at the time your Yahoo GeoCities Site is terminated."

This is the previous version:

"7. Yahoo does not own Content you submit, unless we specifically tell you otherwise before you submit it. You license the Content to Yahoo as set forth below for the purpose of displaying and distributing such Content on our network of properties and for the promotion and marketing of our services. By submitting Content to any Yahoo property, you automatically grant, or warrant that the owner of such Content has expressly granted, Yahoo the royalty-free, perpetual, irrevocable, non-exclusive 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."

(the bit in ITALICS is where the problem lay)

For all the details read James's full story