Zenyatta. Firstly, she's a filly in a sport dominated by dudes, er, colts.
Next, she's undefeated - having never NOT WON a race. Also, in late 2009 she retired. For almost a month. But she's back and ready to make a splash, racing against 2009 Horse of the Year, Rachel Alexandra.
So what's with Rachel Alexandra? She's ONLY the first filly in 85 years to win the Preakness Stakes. And Zenyatta lost Horse of the Year only to Rachel Alexandra, which means the two top Horse of the Year contenders were both fillies. Boo-yah, holla for the ladies.
I talk about this like I know it all, but seriously it's big news.