Bob McElrath writes:
 >
 > MathML adoption has been glacially slow due to the chicken and egg
 > problem between browsers and page creators.  I encourage the AXIOM
 > project to make use of MathML and help push this!

Axiom includes support for OpenMath (http://www.openmath.org/) but it
isn't clear from the mailing list discussion whether anyone has
managed to get it to work with any of the open-source axiom releases.

At http://www.openmath.org/ there is an XSLT style sheets intended to
transform OpenMath into presentation MathML. This could perhaps be
used to process output from Axiom in the absence of support for
generating presentation MathML directly.