Here is a site translating .mobi to .ePUB

It is true that there are many more ".mobi" file then ePUB.
But truth is that as long as you have the Kindle file ".mobi", there are numerous free applications that can translate it to ePUB - Thus allow you to get the book on the iBOOK as well

One such free service you get right here:
Convert Files - free online file converter and YouTube video downloader.Convert videos, audio files, documents and ebooks.

So all my mobi books are already in ePUB as well .

Hi,

You can also use a free tool call "Calibre ebook management". It can convert a lot of formats into ePub. You can select fonts size, pagination, synch, etc

one more online tool, even better
iiiconverter.com