I have published an intial draft of a document I have been working on which attempts to provide practical advice to developers on what ARIA to use in HTML:
Using ARIA in HTML – intial draft
My intention is to provide a non normative resource that fills in the gaps in the current HTML5 specification and a document that is more readable (i.e. less jargonist) It does deviate from HTML5 in some of its suggestions, these deviations are based on current implementation realities.
Feedback/comments welcome!