Before electronic encyclopedias, most people had to go to the library and refer to one or more of the massive volumes that left shelves sagging. A few lucky souls had their own private encyclopedia sets at home, perhaps because they surrendered to a door-to-door encyclopedia salesman in a moment of weakness. However, encyclopedias of the paper kind began their decline when products like Encarta emerged. Electronic information is easier to search and update. (It's easier to copy and paste as well, but that's a touchy subject.)
We've made a complete circle here. Encarta was based on an innovative technology that disrupted an established industry. Now another innovative technology, the Internet and its hive-mind, has turned the tables on Encarta. It only took 15 years for the product to go from dream to dud. It's not that Encarta's information is bad, just that Microsoft can't compete cost-effectively with Wikipedia's free and instantly available information.
With all the changes that have happened in the past decade and a half, it makes complete business sense for Microsoft to close down Encarta. Still, it's the end of an era. Before the Internet, a lot of students depended on products like Encarta for their research. Although the press release says Microsoft will discontinue Encarta as of June 2009, the Encarta site still seemed to be selling the product. So if you want a piece of Microsoft history, act now!