Created in a collaboration between Ray (Rui Wang) and former Wired editor-in-chief Chris Anderson(whose grandfather invented the automatic sprinkler system back in the '40s) is the open source and web enabled OpenSprinkler system.
Originally developed as an experiment in using the "Maker Movement's" new toolkit of digital prototyping, remote collaboration and manufacturing access to create an alternative to off-the-shelf irrigation systems the project is now being sold in both a DIY and assembled version (Arduino or Raspberry Pi based) for those looking to add some intelligence to their backyard watering.
Outfitted with Ethernet or WiFi connectivity the controller can manage scheduling for up to 8 separate irrigation zones, talk with external rain sensors for watering based on actual moisture conditions, and can be controlled remotely using a custom smartphone app or from a web dashboard.
More details about the OpenSprinkler can be found at: OpenSprinkler.com or you can see Ray explain the system in the demo video embedded below.
Additional: Github page