What's the difference between different HDMI cables?

I've been checking out HDTV options recently; it might just be time to upgrade the old CRT TV for something a bit ... flatter ... Everywhere I look - websites and shops - there seems to be this penchant for selling gold-plated-handmade-ultra-this&that HDMI cables. Which puzzled me, because I thought HDMI was a purely digital signal (as opposed to the increase in quality you an get from buying proper analog cables like speaker / SCART etc)

Today I ran across this piece, confirming my suspicions:

One important bit of info to know about HDMI is that the data transmitted by the cable truly is digital — it’s ones and zeros. And that means that digital cables either work or they don’t, unlike analog cables like the other video and audio cables we’re all used to which can degrade the signals they carry if they’re of poor-enough quality. So if a $20 cable works, it’s the exact same as a $100 cable which works… except $80 cheaper.

There you go. Buying a $300 HDMI cable is like polishing your CDs with 'Hi-Fi-oil': not changing the outcome of digital processing...

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