Not sure if it was card error or my error. Just bought a new Transcend 8gb card from Adorama. Used it today at the zoo. Seemed to write files just fine. Got down to the end of the card and I wasn't paying attention. It blinked or something and the LCD showed 1 image left on the counter so I swapped out a new card.
Come over, put the card in the reader, it showed 650 pictures to download. Takes a real long time, showing no program. Then the downloader closes and when I attempt to download again, the card isn't recognized.
Just installed Sandisk RescuePRO and it's trying to working but it's saying the card is "severely corrupted."
Things don't look good friends...
UPDATE: Looks like Sandisk RescuePRO, despite it giving multiple errors during the card scan saying it was "critially corrupted", has successfully recovered all files. They were recovered in .tif format and not .cr2, but they still open up fine in CS3, so looks like all is ok.
Still don't know what happenend. Not sure if I should ditch the Transcend cards and stick to Sandisk, or if the problem came from getting down to only a few shots left on the card.

but here are a few highlights...

