If you click on an ePub download link in the Android browser and get back an error saying "Cannot download. The content type is not supported on the device", then make sure the web server is setting the Content-Type header to "application/epub+zip" and not "application/octet-stream". When you do this, Android will launch FBReaderJ automatically (provided that you have it installed, of course).
You just helped me out. Couldn't figure out why ePub files were downloading properly to PC amnd Mac's but streaming in garbled on Android and iPhone devices. Your little post solved it for me. Don't know how I found it through all the web grabage ;-)
Do I have to be root to get this to work?
Many thanks!