So far all we have seen of HomeKit is promises from last June; there wasn't a way to take advantage of it until iOS 8 shipped, and even now virtually nothing utilizes HomeKit. But that's slowly starting to change, and CES 2015 was the first wave of hope for Siri-friendly home automators.
Philips
While not announcing anything at CES, Philips Hue lights are already so Apple friendly you can buy them in Apple retail stores. Philips has already stated its intention to support HomeKit, but has had nothing new to say since the release of iOS 8.
iDevices
First up, iDevices has the Switch, a block you plug in, then plug a device into and it can be controlled from your phone either with the app or using Siri to say things like "Turn on my home." There's no hub to purchase for controlling the Switch, so you can just plug it in and get Siri integration out of the box. It's a lot like using WeMo switches, but it skips the IFTTT setup steps. TMO's Bryan Chaffin posted a pic of Switch last week at CES:
Elgato
There's also the Eve line of gadgets from Elgato, including door and window sensors (similar to alarm sensors), weather sensors, a water sensor for the plumbing in your house, and a smoke detector (the first Nest Protect competitor). As with a lot of CES announced items, these aren't available yet, but will be HomeKit compatible when they are released. This is an excellent setup for data junkies who want to track data over time.
Loads of data from your house, courtesy of Elgato's Eve.
iHome
iHome is also coming out with a HomeKit compatible smart plug. It is reported to ship in Q2, and come as either a US$40 one-outlet device, or a $50 version that includes a USB port.
iHome SmartPlug
Credit: iHome [via The Verge]
Incipio
Incipio, known for their cases and other mobile accessories, came out swinging with three products: $24.99 gets you either the smart outlet or light bulb adapter, a clever device that makes your regular bulb a smart bulb, and for $59.99 a power strip that includes one smart outlet. Incipio says availability is Q2 of 2015.
Incipio's Smart Outlet.
MobiLinc
Home automation company MobiLinc announced a HomeKit compatible iOS app last September, which is just a feature added to their existing MobiLinc Home app. If you are already set up with a MobiLinc hub, adding HomeKit compatible devices to your setup will "just work" since there's no extra work in the app to use them.
MobiLinc's new app now speaks fluent HomeKit.
Insteon
Pioneers of home automation Insteon have announced a HomeKit app, and also the Insteon Hub, compatible with HomeKit and available for preorder right now, with no ship date listed.
Insteon's new pre-orderable hub.
Litehouse
Litehouse is offering an already MFi certified circuit board for anyone who wishes to build their own HomeKit automation from scratch.
Wither Wemo?
It must be noted that the biggest hole in the HomeKit support list is the aforementioned Belkin and that company's WeMo product line. WeMo hardware is a prime candidate for Siri to boss around, and yet we have had no word from Belkin...until now. In a statement, Belkin noted that it is "actively engaged in bringing HomeKit compatibility to fruition in the very near future." So there is an announcement, but no timeline or details.
This is a list that will continue to evolve, so if I've missed something please let me know!