I do not have a Droid; I have a Samsung Moment which, like the Droid, uses the Android operating system.
I can access my smashwords account through Aldiko, a free ebook reader available in the Android Market. (I specifically signed up for Smashwords because of this.) I would think that I can buy that way as well, since it links up to the web browser to get to the site, although I have never tried it. If I wasn't at work -- where I can't have any sort of camera -- I'd check for you.
However, it shouldn't take long for someone to come in and agree or disagree with me.
