Z-Wave might be "standardized", but it doesn't mean any Z-Wave device will work with any Z-Wave gateway, as the gateway needs to understand what kind of sensor it is, or you won't be able to control it. That said, the same goes for ZigBee. That said, what we've found is that many ZigBee devices that we haven't even tested, still work, such as the Quirky door sensor, the GE and WeMo bulbs etc.
All home automation gateways that support ZigBee would be supporting the HA profile, although this is set to change from next year when there will be a transition to ZigBee 3.0.
If the Orbit sprinkler controller works as a binary switch, then we might support it, but even so, there are about four or five different types of binary switches, so there's no guarantee it'll work.