the problem with mathematical notation and formulas isn't just a publishers' issue (some issues are reviewed
here): at the moment there is no standard for mathematical notation in EPUB (yet).
EPUB3 should be implementing MathML, but even if this finally happens, we'll need ebook reader manufacturers to catch up and enable the devices to "read" such standards. Of course, this si not a problem if you read on a laptop, as MathML can be easily read - not so, unfortunately, on e-ink devices.