<update>June 7, 2011</update>

Since announcing the release of the EPUB 3 specification, the blogosphere and tweet streams have been alive with the sound of music to publishers' ears. No doubt Amazon's news that it will finally accept EPUB also adds to the collective hallelujah chorus.

While there is already an abundance of information, news, and opinions on EPUB 3, this post aims to highlight what features and functionality are most important for publishers to understand:

• Improved accessibility support---It's a big deal that DAISY is converging completely with EPUB 3. This will promote rapid take-up of the standard in education and government segments. 
• MathML support---this alone garnered hoots and hollers from RSuite's tech team. No longer must STM publishers sketch out equations as art.
• Embedded fonts---the look and feel of your PDF is maintained because publishers can deliver fonts along with the epub file.
• Improved SVG support---vector graphics mean images scale with your pages and pages are "lighter" thus loading faster.
• New and improved metadata---who doesn't love publication metadata that can include specific handling and distribution instructions!?
• Video and audio support---publishers can synchronize audio with text. This will also raise the bar for all of us, e.g. enabling switching seamlessly between listening in the car and reading at home!
• Javascript---scripting offers chances for interactivity, think forms, etc.
• Layout---multiple columns, hello! Ladders and widows and orphans, goodbye!

We'd love to add your opinions on new functionality to the list. Leave a comment and I'll continue to add on to the bullets.