Ok, so I have gotten caught up int the quest race as well.
 
Stepping back, I think that the quest system system is really indicative of a potential new trend in content sites.  Traditional publishers still think in a very one-way fashion -- we write stuff, you read and maybe comment.   Giant Bomb demonstrates that that model is stale and dying.
 
GB is truly a community and like all communities you are part of it for fun, companionship, and because there are shared interests.   Quests provide a mechanism to value and reward people for actions that benefit the whole.  And like all things that good, it remembers to make it fun and authentic.
 
I look at the quality of the site and discussion and wonder how traditional publishers compete.