In the past we have had contests like these and done the voting entirely internally to choose the top 3 and an honorable mention. We thought it would be fun and positive to narrow down to just the top 10 and let our users vote to determine the "people's choice".
As Jason points out it would take many hours or even days for anyone to go through all of the sites submitted and give an informed vote, so it really wouldn't be practical to expect our users to actually evaluate all 200+ submissions. They would either vote for one of the top 10 in the list or wouldn't bother to vote since they couldn't possible make an informed decision.
This is just one vote, not the only thing we are doing around the submissions. When we announce the winners we will have an opportunity to list more of the many great sites that were submitted.