Ah the synergies, Sam Ruby talk about getting MathML supported in planet, and the Ephox weblog talks about getting EditLive! for Java to automatically upload image versions of MathML equations so they render in any browser. The nice thing about this function of EditLive! is that you can still just double click the equation image to edit it again – the MathML is stored as an encoded attribute so that information isn't lost.
Unfortunately, there isn't a standards compliant way to reliably preserve the original MathML and not have it get in the way of the image, but an extra attribute doesn't cause harm in any browsers. For the record, if you do want to get the original MathML back out of the attribute, it's just URL encoded so it's pretty simple.