The post gives no specific details, but in response to a customer question about whether existing Hue lights will work with HomeKit, Philips confirmed that they will.
Yes, the solution we are working on will work with all your existing and new Hue lights. To get details about how your existing Philips Hue products will work with HomeKit, please follow us on Twitter or Facebook
The most likely approach is that Philips will offer a hub to act as a bridge between HomeKit and existing Hue products. The company says that it will reveal full details in September.
An Apple support document recently confirmed expectations that the Apple TV will act as a HomeKit gateway for controlling devices from outside the home.