MathML 3 just became a W3C recommendation, so we've written some information up about the new features in MathML 3 and what problems they solve. There are too many new things to list them all here, but some of the major ones in presentation MathML are:
- support for linebreaking and indentation;
- elementary math support;
- bi-directional text support, especially for Arabic languages;
On the content side of MathML (the elements aimed at semantics, not display), there has been a huge amount of work to align MathML with OpenMath. The other big deal about MathML 3 is that it is a part of HTML 5, a replacement for HTML 4 that has a lot of people excited. Being a part of HTML 5 means that MathML steps out of the shadows of being an XHTML-only solution.
For a complete list of changes, see our pages and examples for what is new MathML 3. I'm happy to say that the forthcoming version of MathPlayer already passes 98% of the 1,680 tests at the W3C. Not bad for something that just became a recommendation!