The Youtube link posted above may help. At some point in the talk he mentions it and the paper from where it came. I can't find it in a quick look at his site: http://www.myharddrivedied.com/ but a deeper dig around may get you there.

I know the theory behind how it might be done, but AFAIK it's never been done. I'll keep looking, but I haven't found anything about anyone actually doing it for real.

Are you talking about the infamous:
http://en.wikipedia.org/wiki/Gutmann_method

see criticism section. I agree that it is a voodoo incantation.

That's a good read - thanks.

With the single wipe it is alleged that some forensic recovery is not impossible, but the amount of work and time - versus the reliability of the result would be be interesting to see in the wild. It must get even more complex if the file system is encrypted.

For the average 'sold on eBay' type of drive, it's pretty safe to say a single wipe of any pattern will render data unrecoverable with the caveat of any sectors that are marked as bad during the life of the drive. It may be possible to recover data from them - but again I see nothing more than suggestion or theory on this.

For me the Secure Erase method is a winner in my eyes. It does not consider sectors, it wipes tracks, it's fast and it's to DOD standards.

From the Secure Erase FAQ (it's a Word document, an interesting read):

Q: Is any data left after a secure erase?

A: Investigations at CMRR at UCSD have shown that a single pass secure erase at lower frequencies results in no remaining data signals and a second erase reduces this signal only slightly more. The resulting data signal to noise ratio (SNR) at the magnetic drive head is below that required to recover data using a disk drive channel1. The only recorded signal left in these experiments is a small amount of highly distorted track edge recording which is extremely difficult to recover data from even if the disk is removed from the drive and tested on a spin-stand.

EDIT: "channel1" is my mis-transcription of "channel" with a reference to Secure Erase of Disk Drive Data, Gordon Hughes and Tom Coughlin, IDEMA Insight 2002, http://www.tomcoughlin.com/techpapers.htm

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That's a very good paper, I will save it for future reference. Well, I guess the conclusion is that if you want to be extra sure, you can do a one or two pass random erase. However, even they say that the error rate for recovering even 1 pass zeroed is quite high.