[Valloric]

The best thing about the iPad with regards to epub?

Adobe Digital Editions stops being the reference renderer.

Competition FTW. Maybe Adobe will pick up its game now and fix the five bazillion rendering bugs & quirks. If they don't, they'll just become irrelevant.

If you're a publishing house and your epub doesn't look right in iBooks (or whatever they're calling the built-in epub viewer on the iPad), you don't release the book. You work on it until it does, since that's what the vast majority of your customers will be using. Not now, but in six months to a year, definitely.