I would prefer an online tool so that I am not tied to a particular computer for adding content. Additionally I would expect an online collaboration tool ( distribute chapters to authors and editors) to collaborate with other authors and editors. Exporting to ePub and PDF is a must have requirement.
I have heard of 2epub but I have never used it nor would I believe you would get a good quality ebook. I would suggest doing this with InDesign that will allow you to create
You can export as an
Google Drive has live collaboration and is totally in the cloud. It can export PDF files and HTML files that can be easily converted to ePub.
This may also be possible with Microsoft Skydrive, but I am unfamiliar with that suite.
I am a founder at memobuild, an online book/document editor with collaborative features and export to ePUB and PDF. It's oriented toward technical writing, so if you're writing a novel it's probably best to use something else. But for technical books, reports, manuals, etc... it's a great fit.
Note: We're currently in closed beta, but if you register I'll be happy to include you.
You can use Papyrus (http://papyruseditor.com) to create books in PDF, Epub and Mobi(Kindle) formats.
Disclosure : I am the creator of this site.
Mac OS Pages program File -> Export --> Epub...