Interesting post from Dave of RELAX SEO about the xFolk Cloud Generator which references SIOC:

xFolk Cloud v0.5 beta released | Performancing.com

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I wasn’t going to do this but … here is a bit of a brain dump from the think factory here. We think that ‘Tagging’ is like ‘Candy Cigarettes’, A way to get people smoking/thinking ‘Classification Theory’, we know that the only real way to SEO nowadays is RELEVANCE RELEVANCE RELEVANCE, and there are just too many flaws in Tagging to ensure a lasting value. Semantic Inter-linking will most likely rule the day … like a localized phone book … you subscribe to the cloud and have your info on tap. If you don’t know about SIOC (semantic web) well, your reading the wrong Blog, best you find some SEO guru who will tell you that ‘on the page SEO’ is out and begging for links is ‘in’.
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More here.