From the WTA Site:
The award honors the player who has demonstrated the most intuition throughout the year. Venus joins illustrious past 6TH SENSE winners that include fellow former No.1s Justine Henin (2005, 2007) and Maria Sharapova (2006).
Williams was one of 10 players short-listed for the award via an online competition organized by Whirlpool, Premier Sponsor of the Tour. Fans from across Europe were invited to view the 10 nominees online and vote for who they felt demonstrated best the 6TH SENSE attributes - intuition, intelligence, precision. There was a new format this year, seeing two pools being introduced, with Williams winning the first pool and Ana Ivanovic the second.
From the two finalists, Williams was chosen as the 6TH SENSE Player of the Year by an expert panel that consisted of former great Conchita Martínez; Eurosport's chief commentator, Sam Smith; and leading tennis correspondent and member of the International Tennis Writers Association, Barry Wood.
So this isn't a WTA award, right? And why is it only voted on by European fans? That seems weird. All that being said, I can't think of anyone else that deserves it as much as she does.