Jeni Tennison has written a wonderfully insightful post on RDF and HTML5. She caps it off with two sentences that every RDF advocate needs to pay attention to:

• so why not just stop arguing and use the spare time and energy doing?
• so why not demonstrate RDF’s power in real-world applications?

That's all there is to say really. Stop waving hands around promising things will be great if only you did X. Get out there and build some things that actually make a difference.