Smashwords ended the beta test today, but the eDelivery service is only about half as useful as I had hoped. They have unfortunately had to drop support for emailing ebooks to your Kindle. Here's how Smashwords phrased it in the email they sent out today:
Unfortunately, due to Amazon policy, we will not be able to release Send to Kindle at this time.
I don't know if it is true or not but it certainly sounds plausible. Amazon is often inscrutable to the outsider, and they have in the past blocked 3rd party services like Lendle and Findings. It's possible that Smashwords couldn't get the feature approved by the relevant parties at Amazon.
But never mind what we can't do; instead let's look at what we can do. Smashwords customers can now have their ebook purchases synced to a Dropbox. It takes a little bit of work to set up, but once it is readers will have a personal cloud library akin to the Kindle Cloud.
Yes, it was always possible to upload the files yourself, but I'm lazy so I appreciate the automation.
You can find instructions on how to set it up here.