Just a note: I tried this technique with the CF adapter with my A900 and it doesn't work
The culprit is the CF adapter which with the A900 body doesn't let the Eye-Fi card connect to the WIFI network. We really need a CF version of the Eye-Fi... For now, there is no way to tether the A900 with an iPad (of course, through a PC this works fine).
The iPad can read the A900 raw files though if you connect through USB with the camera or a CF card reader and it displays the embedded JPG files which is usually good enough for preview.