This is now official: the OpenSpinkler Pi (OSPi) has just been released. Basically, it’s a sprinkler extension board for the Raspberry Pi. If you are interested in using Raspberry Pi to control sprinkler valves, you can now do it directly through the GPIO pins, without another layer of microcontroller and Ethernet controller. Better: the Raspi and OSPi can be fixed together and put inside the existing OpenSprinkler enclosure (albeit quite tight). The OSPi also has expansion board connector, which allows it to link to standard OpenSprinkler zone expansion boards to enable more stations. Here is a blog post about OSPi:
http://rayshobby.net/?p=5339
Keep in mind that the software demos are very primitive: they are meant as a starting point for future development, and are nowhere near complete as the full-featured standard OpenSprinkler. Dan in CA has been very generous for helping me to convert the OpenSprinkler programs to Raspi. A small number of prototype OSPi boards are available on my shop page (http://shop.rayshobby.net). If I see sufficient interest in it, I may consider making it a more permanent product.