@ChaoscripT: the valve shown in your link is clearly a latching solenoid (note that the two wires have different colors, meaning there is polarity). Latching solenoids are typically used in battery-powered controllers, and CANNOT work with 24V AC sprinkler controllers (such as OpenSprinkler or OSPi), because the electric spec and the controler mechanism are completely different. OpenSprinkler Bee is designed to work with latching solenoids:
http://rayshobby.net/?p=8527
We have an Arduino Shield version of OpenSprinkler Bee (called OSBee Sheild) that will be released shortly this week.
24V AC valves require a 24V AC power adapter and cannot work on batteires. If you must use latching solenoids, then OpenSprinkler or OSPi are not suitable. If the valve type doesn’t matter, I suggest that you get 24V AC valves, they are cheap and widely available online or at home improvement stores.