It would be useful to identify the primary driver for this increase in demand for HTML5. Is it iPad/iPhone compatibility? Buzzword compliance? How many clients understand what they're getting when they hire someone with this skillset? And have we defined what the HTML5 skillset really entails?

Can I say I am an HTML5 developer because I know to change the DOCTYPE and wrap items in <header>, <section> and <article> tags? Or should the expectation be the ability to produce Flash-like entertainment-oriented sites with audio, video & canvas animation, or web apps that make use of local storage and offline capabilities? It's a pretty wide range of skills.