Compare these two pages:

http://cvs.gnome.org/viewcvs/yelp/src/yelp-db-pager.c?rev=1.62&view=log
http://svn.gnome.org/viewcvs/yelp/trunk/src/yelp-db-pager.c?rev=2560&view=log

With the CVS page, I can tell that revision 1.61 was tagged with YELP_2_15_1 and YELP_2_15_2.  When trying to track down the source of a bug, this is incredibly useful information to have.  With the SVN listing, there's no way to get that information short of manually looking at all the directories under yelp/tags.

I realize that SVN doesn't actually have real tags (a design mistake, IMO).  And I know that, while SVN knows where the tags were copied from, it doesn't know where things were copied to.  So this probably isn't an easy thing to do.

I think this could be accomplished by storing the branch point information in a database on the server.  The database could be updated by a server-side hook or by a cron job.  Then viewcvs could just look up entries in the database when it displays the history of a file.