I think there are two questions here. First, is openoffice, and Kovid answered that. Second, is latex, and that's interesting.
You can do a rough job with latex2html, but I don't know how clean that comes out. I haven't had great luck. IMHO what you really want to do is preserve links (to equations, references, toc, etc) in html and transform vector graphics -> svg and equations -> mathml (also svg) (and, of course, raster graphics as png). Then try converting that into epub ...
There are some tools out there that nibble on this problem (texvc and svglatex), but I'm not aware of any good solutions. (Is converting the entire document to svg a good solution? I can do that, but it's really no better than pdf. You need integrated html and svg.
You could also work through pdf intermediaries, since pdflatex is pretty advanced, but that creates other problems.
I'm keen to see what I can do with svg and html epub books, and to see how the prs-505 can handle svg (??) so I'll be playing around with this problem and will report back if I manage anything useful.
Addendum. This may be useful:
http://www.w3.org/Math/Software/math...onverters.html
HEVEA (
http://pauillac.inria.fr/~maranget/hevea/) looks particularly interesting.