I found this really informative:
http://www.pcper.com/reviews/Editorial/ ... -ExplainedYou might have noted empty space before the first partition of an SD card. This space is actually a part of the SD specification and some cards treat this area differently than the rest of the flash on the card. Some people love to reformat their SD cards to get that tiny bit of extra space back, but this is not recommended for several reasons. Placing the 'improperly' formatted card into a camera or video recording device that has firmware optimized for 'standard' SD formats may corrupt the partition as it is not where it expects it to be. Improper partitioning may also result in the partition being physically misaligned with respect to the flash area, which may throw off any wear leveling routines and wear the flash at an accelerated rate. If you've reformatted all of your cards and are now getting that sinking feeling, don't worry, there's a way to get them back to where they are supposed to be...
