As some of you might have noticed, the sourceforge-provided SVN browser has not worked for the past 24 hours.

The error you are seeing is related to the services downtime that is detailed here:
http://sourceforge.net/apps/wordpress/sourceforge/2011/01/27/service-downtime/

This will be fixed once the downtime is over. You can monitor the following for updates:

Site Status: http://sourceforge.net/sitestatus
@sfnet_ops on Twitter: http://twitter.com/sfnet_ops

UPDATE: Since 07-Feb-2011 the ViewVC for SVN has been restored.