But here's the core:

Yesterday, in the Site Updates section of the Smashwords' website (you need to be logged in to see this) Mark Coker posted:

Quote Originally Posted by merk Coker, CEO of SmashWords
December 28, 2012 - Smashwords Direct alpha testing underway. We're preparing to launch Smashwords Direct, our direct .epub upload option. One year ago in my 2011 annual year-in-review over at the Smashwords Blog, we made a commitment to launch SWD in the second half of 2012. We're working to fulfill that commitment. We're nearing completion of a beta version of SWD. The first iteration will enable those of you with professionally designed .epub files to replace your current Smashwords-generated .epub with another .epub. It'll also allow authors to upload .epub files instead of Word .doc files. We're inviting people with custom epubs to email them to us...
I can't link directly to the Smashwords page, but go, login, and you'll see the announcement.

Send 'em your ePubs. I'd suggest a short note in the email telling them how the file was generated and validated.