This efficient ways to store graphs in MySQL will come in handy.
The RDF/A draft for embedding RDF in XHTML has been released. I did a quick look at the spec and it does look good — the microformats people will be happy to see it.
I still believe that we don’t need to embed RDF directly into our web pages because many web sites are dynamic now. As such, if one accesses the page as a human, you get data formatted for human consumption through a browser; if you access the page as a webbot, by attaching /rdf to the end of the document, the same data is formatted for mechanical consumption. No need to clutter up web pages, or make page creation or generation that much harder.
However, have said this until blue in face, and am left feeling like tree falling in forest. So I’ll just point you to the spec while I do my own thing, secure the knowledge that it doesn’t matter how the data gets there, it’s all compatible thanks to RDF.