Originally Posted by lorenzoens
ePub is the international standard, on the opposite, Mobi is older, rough and limited from a typographic point of view.
That's not completely true. Both mobi and epub are based in a reduced HTML tagged XML.
Mobi is actively maintained by Amazon, and it has some things that ePub doesn't (at least version 2) like DOM extensions and an standard annotation formal. One mobi or prc annotated ebook can be viewed with its annotations in any standard program (like Mobipocket Reader for PC/Windows Mobile/Windows CE and Kindle).