Hover buttons, pretty cool, but not well explained in the documentation that I have found. Hover buttons add a cool effect and cause hovering of an object over another object to appear to be similar to a click.
The best examples of using the Hover buttons are found at: http://raychambers.wordpress.com/2012/04/04/kinect-mix-and-match/
Ray Chambers uses the skeletal tracking template with hover buttons makes a mix and match game. I used his work to implement a template that I will share over the next few blogs (really, really!). I did the Kinect for an instructor in High School, but I need to sanitize the product to protect the instructors general idea.
Ray is generally a good source of ideas, and usually does a presentation of his code in a manner like most of us write code. It is easy to figure out what he is doing and then you can write your own.
So take a look at the link above.