GData output is usually ATOM / RSS e.g plain xml. This feature enables users or admins to preview the server output as html transformed by user defined xsl stylesheet. Stylesheet is configurable per service.
That's just a cool feature for developing and for users wanna use the server for simple blog or feed server.
regards simon
HTML output:
http://javawithchopsticks.de/gdata-server/feed/weblog?alt=html
RSS output:
http://javawithchopsticks.de/gdata-server/feed/weblog?alt=rss
ATOM output:
http://javawithchopsticks.de/gdata-server/feed/weblog?alt=atom