I thought I would start a thread on this, can't see one currently.
EOS 7D Mark II, EOS 5DS and EOS 5DS R cameras only.
Communication with Smartphones
Images can be viewed, controlled, and received using a smartphone. MP4 video can be viewed and saved using a smartphone with the EOS 7D Mark II camera only.
Remote control of the camera using a smartphone is possible.
Remote Operation Using EOS Utility
Remote control functions and image viewing functions of EOS Utility can be used wirelessly.
For the 7DII needs a firmware update Firmware 1.1.0 for Canon 7D Mk II is up at Canon USA - enables Canon's Wi-Fi Adapter Kit
Notes from the Canon page
** Compatible with iOS versions 8.0/8.1/8.2/8.3/8.4/9.0/9.1/9.2/9.3, Android™ smartphone and tablet versions 4.1/4.2/4.3/4.4/5.0/5.1/6.0. Data charges may apply with the download of the free Canon Camera Connect app. This app helps enable you to upload images to social media services. Please note that image files may contain personally identifiable information that may implicate privacy laws. Canon disclaims and has no responsibility for your use of such images. Canon does not obtain, collect or use such images or any information included in such images through this app.
*** The Wi-Fi Adapter W-E1 must be inserted into the available SD card slot. The W-E1 does not have storage and is not designed to record images. To record and store images, a CompactFlash card must be used in the dedicated CF card slot.
Wireless communication may be terminated if the user operates the power switch, card slot cover, battery compartment cover or mode dial; starts Live View shooting or operates the movie shooting switch during wireless communication.
The communication distance for the Wi-Fi Adapter W-E1 is approximately 32.8 feet, making it shorter than the built-in Wi-Fi® communication distance of the EOS 80D camera (approx. 49.2 feet).
Because wireless communication speed can slow down or be interrupted when the grip is covered by a user’s hand, Wi-Fi® connection is not recommended while holding the grip.
If the EOS 7D Mark II, EOS 5DS or EOS 5DS R cameras are turned on or the shutter button is pressed while only the Wi-Fi Adapter W-E1 is inserted, [Cannot record] will appear on the LCD monitor.
If the Wi-Fi Adapter W-E1 is inserted into any EOS camera other than the EOS 7D Mark II, EOS 5DS or EOS 5DS R cameras (firmware V1.1.0 or later) and the power is turned on, [Card locked] or [Card error] may appear on the LCD monitor.
When the Wi-Fi Adapter W-E1 is inserted in the camera, a USB cable cannot be used to connect the camera to a Connect Station, wireless file transmitter, printer, etc. It can be used when the camera is connected to an external monitor via HDMI cable.
Communication with a smartphone is not available during Live View shooting or movie recording using the movie recording switch.
Image display may be delayed, and images may not display smoothly while using the Wi-Fi Adapter W-E1 in an area where devices that operate on the same frequency band are in use, such as Bluetooth® devices, microwave ovens, cordless telephones, microphones, smartphones or other cameras.
Image display may be delayed, and images may not display smoothly if a person or other obstruction comes between the device you want to connect to or the access point antenna.
So effectively you will loose the use of the SD slot for storage and it doesn't sound as if a CF>>SD adaptor could be used if you are one that prefers SD cards.
Pre-order in the UK is expected in October £39.99.
In the USA $39.99, can't see a date but probably before the end of the month.