Hacker News Reader

(it's really not an answer, but just in case you haven't seen it already, here's an online version which is actually prettier than the epub one: http://addyosmani.github.com/backbone-fundamentals )

Calibre is an open source e-book management software that you can use to read an .epub or convert to .pdf

http://calibre-ebook.com/

I found an online epub -> PDF converter. It didn't come out that great but it lets me browse the contents until I can load the epub on my tablet.