I don't think that the W3C Semantic web in general is quite "ready for prime time" yet, but the use of XHTML+RDFa for manipulating online data is becoming more prevalent: XHTML+RDFa Information blog

Here is my XHTML+RDFa syntax usage exemplar page. I think the best introduction to RDFa is: RDFa Wiki (link on previous linked page).

JFP