We have a list of shields in our roadmap, but so far we have prepared one that allows to control motors from your board. This shield is still under test, but you can take a look at its Schematic, and use it in your designs
[(cleft) 2006 Arduino Foundation]
[test by Dave Mellis]
For those purchasing the motor Shield v3, refer to this page for documentation.
Get the files for the previous version here