Yesterday I lost all my images of the day from card failure. I had been able to review the images in camera as I worked but after taking the card from the camera and immediately inserting it into the card reader - nothing. On going back to camera, nothing - no images. This was my most recent card purchase, a 4 GB Sandisk III - a bit disappointing. So far it's worked fine today for the previous dust tests so we'll see.
I was able (as always) to rescue the images via PhotoRescue. This commercial software has never let me down, generally rescuing 99% of all the images (in this case all but one of 105 images) - not bad in my book and essential to anyone's work flow. While cards do come with image rescue software, it has never been as effective as Photo Rescue and I highly recommend it. I note that they now have three versions, I have the $29 expert version and so far have not had to use any of it's more sophisticated rescue techniques.
My routine is to let a card fail once and I'll reformat as usual and keep using it, but if it fails again within a month or so - it's history. Don't know if this is efficient use, but it works for me - especially with cards coming down in price as they have.