Hi Phtoo, I have been through the mill with this one over the past few years, I have lost images, thankfully they were well after the event and not really important, I shoot weddings and definitely wouldnt want to loose any of those images. my workflow is as follows:
I shoot RAW, usually during the meal I backup all used cards to my macbook using a lexar Firewire 800 reader, its quick compared to USB and I'm sure there are even faster now!
I also if time permits backup to a Lacie rugged FW800 drive, at this stage I have the images on my CF cards, in my Aperture library and backed up to my HD, 3 places, I keep all 3 bits of kit in different places, i.e. the CF cards are on me, the macbook is with me and if my HD is back in my van.
When I get home and sort the images out I do the following:
Check HD is good, macbook Aperture library I export as a library to my big mac as the HD on macbooks isnt that large I then after checking delete the library to free up the space on my macbook. I format my CF cards.
After editing the rubbish out and selecting usable images and batch processing I back up these to Amazon S3, usually the best of the bunch in JPEG format (Amazon S3 is cheap as chips) I can now work on my images confident that if the failure/theft/accidental loss of data occurs I can get the images back, the reason I use off site (Amazon S3) is simply because if my house was to burn down (hopefully it wont) I can get back to my images in an emergency.
I'm sure there are a lot of alternatives to this and different ways of doing things, most importantly though is after a catastrophe can you still get to your work? hope this helps.