I've previously written about Prowl, the generic push notification app for iPhone. Initially designed to work with Growl, it now has grown to allow direct access. There's a whole bunch of plug-ins available, so now it's easier than ever to tie the excellent Prowl into your home automation system, from your platform of choice.
In a related note, for an example of how to use the direct access via AppleScript and XTension, see Sending PROWL iPhone Alerts from XTension.