It's basically a heavily improved var_dump and debug_backtrace version with some advanced behind the scenes action. The features description is in the google code page: http://code.google.com/p/kint/ but the interesting part is that this is the only dump tool, that can display the name of the dumped variable as well as use modifiers on the calling function.

The flow is traced back to its origin class/script and a token parser is used to find where the value was created. You can see a sample of how to use it over on its Google Code page. This also includes screenshots of the output and the configuration values you can set for things like a display path callback and the maximum number of levels to traverse through. You can download the current version here.