Well, it looks like the issues with EyeFi may not be a problem for Canon shooters. At least, not all Canon shooters. A couple of weeks ago, Digicame-info reported that instructions and specs for Canon’s new W-E1 WiFi adapter had been leaked. One point of note was the listed dimensions. 24x32x2.1mm; the same as the SD card specification.
Now, new leaked photos confirm that this seems to be true and it is an SD card. Also leaked is some camera compatibility. Interestingly, the impending 5D Mark IV doesn’t appear in that list. This may confirm the rumour that the 5D Mark IV does, indeed, have built in WiFi.