I was looking for some low level formatting tools and found this interesting piece of information:
http://sdprob.aximsite.com/

What is interesting is this part in particular:
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" And of course digital cameras, PDA's and 99% of the rest of the SD card devices need this "secure area" like you need another hole in your head. But guess what? You can't get it back. You can't format the "secure area" (Unless someone out there in webland knows of a consumer device that supports a low-level format) . Its under the control of the SD card's internal controller.

And guess what happens if the "secure area" becomes corrupted? Say bye-bye to your SD card... A high-level format can't directly access the secure area.

(Actually I'll admit the most common question is - why did my SD card go wrong? You should find the answer on the line above...)"
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So, most likely this reserved "Secure Area", present on all types of Secure Digital (SD) cards, might have been corrupted on permanently corrupted cards?

This begs to the question if anyone has had permanently corrupted MMC cards? AFAIK, MMC cards do not have this "Secure Area", since they do not have Digital Rights Management feature in them... Anyone messed up MMC card beyond repair on N800?