So you're making a game. How do you make it nice and perform well on your player's computer? What hardware do end-users have? We think those are very important questions. So here's what we do:
When installed, Unity Web Player submits anonymous hardware details. This is done only once, and does not contain any personally identifiable information (see the EULA for what exactly gets sent). We compute statistics of this information. This can be incredibly helpful for Unity game developers in helping them to make good content decisions and optimize performance of their games.
The hardware data comes from users who installed Unity Web Player, so it represents combined statistics of all Unity game players. Your particular game might be targeted at different type of users with different hardware; and players of your standalone game might have different hardware as well.