Holtzbrinck, a giant German family owned publishing conglomerate you probably haven't heard of, actually owns Macmillan, who you might have heard of, who own Tor, who you probably have heard of if you're part of the regular HN demographic. A few months ago they came to the same conclusion, and have dropped mandatory DRM on genre fiction titles. I believe they're also open to arguments both for and against DRM on other publishing categories, rather than maintaining the doctrinaire "DRM on everything" policy of some of the other Big Six.
The long term effect of this policy is ... well, it remains to be seen. Because publishers traditionally sold to wholesalers who sold to bookstores, they don't routinely sell direct to the public. A move by any of the big publishers to set up a direct-sales channel for ebooks, rivaling Amazon or Barnes and Noble, would probably be seen as hostile or monopolistic by the bookseller trade, and might even generate anti-trust lawsuits! But I'd be unsurprised to see one of the Big Six (now Five) follow the example of smaller direct-sales publishers sooner rather than later -- like http://www.webscription.net/ for example.
Heck, even the publisher stands in risk of being disintermediated here, let alone Amazon functioning as essentially a fourth party in the relationship.
Whereas I find they bring me a lot of value as an intermediary of physical goods. Sometimes I try to order something straight from, say, a food vendor, but always end up choking on the fact the food vendor wants to charge me $15 shipping on my $30 order, because the food vendor's idea of shipping is the local Fedex drop point and Amazon's idea of shipping appears to involve some sort of teleportation technology.
Only if you don't know what a publisher does. See also:
http://www.antipope.org/charlie/blog-static/2010/02/cmap-2-h...
Which in your domain, they probably will. But this is one way of viewing the ever-growing academic revolt against Elsevier. They do a couple of their duties OK, but the whole bundle they are providing is increasingly less compelling vs. what they are trying to charge.
Currently, of the two DRM-laden e-mediums Amazon sells (books and videos), both have DRM because the publishers insist on it.