Google Glass is probably going to be used for many wonderful things. Capturing sporting events while simultaneously engaging in them may not be one of those things.
Legendary tennis star Roger Federer posted a video on his YouTube page of him playing tennis while wearing Glass. The video is a mix of actual cameramen capturing Federer and his opponent playing the game and actual footage recorded by Glass. As expected, the shots from the cameramen were steady and followed the action fairly well, while the footage from Glass was so jittery it kind of made me want to puke.
That's not Glass' fault, per se, but it shows the limitations of having a camera on your head in an activity where your head is naturally going to move around a lot. You can check out the video for yourself below, but be sure to grab the doggy bag before you click play.