Sorry for reviving this old thread; I was looking for a way to convert a LaTeX document to EPUB and when googling for "latex epub", this thread actually comes out on the top.
Just wanted to add another tool to the list.
- plasTeX: written in Python, produces very clean XHTML output, which can then easily be converted to EPUB. The current developer snapshot even contains an EPUB renderer, so it may be able to produce EPUB files directly in the future.
http://plastex.sourceforge.net/
I just used it to convert a novel length book that had all sorts of LaTeXy shmonck in it for printing (source files split by chapter, fancy headers and the like), worked without a hitch, without any changes to the original LaTeX source.