I would like to see a plugin for Insteon Home Automation. It is one of the more popular HA systems and would provide a great way to have a whole of house controlled by voice.
Insteon users can try using VC's built-in scrape action, as discussed in this thread: http://voxcommando.com/forum/index.php?topic=1395.msg12148;topicseen#msg12148
See also: http://www.leftovercode.info/smartlinc.html