Hi,
This is from the eye-fi web site on the compatibility of the G1X, but I think it applies to most powershots:
Known Issues
When an Eye-Fi Card is used in the Canon PowerShot G1 X, the camera automatically disables the Eye-Fi cards wifi when the shutter is pressed. Once a photo has been taken, the camera then re-enables wifi on the Eye-Fi card. This has the following effect:
If you are transferring via Direct Mode your connection will be lost and your Eye-Fi X2 card will automatically restart the Direct Mode sequence.
If you are transferring via wifi your connection will temporarily be lost and the Eye-Fi card will automatically reconnect to the network.
We apologize for this user experience and are working with Canon to change this behavior.
Does anyone have any comments on this? Could CHDK help? Keep the power on to the card?
CHDK does work on eye-fi cards.
Jon