Quick real-world demo of controlling lights with Siri commands via Apple’s HomeKit on iOS 8.3 (iPod touch 5th gen.)
Product used: Caseta Wireless Smart Lighting Dimmer Kit (with plug-in modules) - available at Apple retail stores.
Also available with in-wall dimmers as a kit on Amazon and other online retailers: =s9_al_bw_g60_i1
Quick review of the Caseta Wireless Lighting system here:
Recap of HomeKit stuff at Apple’s 2015 WWDC