Somewhere a gun must have gone off. Harper's announcement this morning of their 'widget' marks the start of new race in publisher services. At least one other large publisher I know has their own plans for a widget, and my guess is that others may join the race as well. There are two big advantages to these widgets that may not be obvious from the press release.
The first is that widgets can be dropped into any blogsite or "social network". A social network is any site (blog, traditional website) where there is a community of people with common interests. It's easy to do, and it almost acts like a free 'banner ad'. Therefore, smart internet marketing types will start mailing the 'links' to their widgets to the social networks they know about who may have interest in there books. Harper has yet to show how their widget can be 'dropped on to a social network', but I expect that in the near future, they will.
The second is that if the repository that stores the content is large enough, then the larger internet providers may not need copies of every .PDF that you create in order to display your titles. All they need is the address of the widget. This helps publishers protect their copyrights, and still makes (as much of the work as the publisher wants) available to the public for viewing. So, when Google and Microsoft, and Yahoo! and Amazon come asking for your .PDF files, all you will have to do is point them to the links for your widgets.