I'm lucky enough to have extraordinary friends who also teach me many interesting things about web standards. Recently I was talking with a friend of mine who's an expert of accessibility applied to electronic documents. I asked him a direct question: do screen readers support the new HTML5 elements? Unfortunately, the answer was negative. Screen readers are still not able to recognize HTML5 elements as they do with normal XHTML elements. For example, they don't provide a way to navigate through all the header elements as they do with XHTML headings. And when it comes to WAI-ARIA, remember that screen readers are not browsers but they simply read aloud what browsers pass to them. So if a browser lacks of support to a certain standard, screen readers won't be able to compensate this lacking in support. So on my websites I use a compromise: transitional HTML5.
With transitional HTML5 I mean a well-formed and validated HTML5 markup but without the brand new HTML5 elements. To be more precise, the only change in syntax takes place within the head element, where I use the new grammar for meta tags and link elements.
I also use an XHTML-compatible tag syntax. By doing so, I will always able to switch back to XHTML if needed. As its name implies, this solution is temporary. Until user-agents and screen-readers will be fully HTML5-compliant, I will stick to this solution.
Remember that XHTML Strict elements are fully HTML5-compatible for the most part of them. I don't want to jump on the bandwagon of this new trend until such a trend will become a solid and stable W3C standard (now is a draft).
But I follow this trend very closely, waiting for new things to come.