On October 31, 2009, MSN Encarta Web sites worldwide will be discontinued, with the exception of Encarta Japan, which will be discontinued on December 31, 2009. Additionally, Microsoft will cease to sell Microsoft Student and Encarta Premium software products worldwide by June 2009.
The announcement from Microsoft didn't mention Wikipedia by name but the competition from a larger, free service has to be the reason. Wikipedia is the largest encyclopedia in human history having more than 2.6 million entries in English alone plus many others in more than 10 languages. Wikipedia's articles reportedly are as accurate as its commercial competitors' products. (See http://news.softpedia.com/news/Is-Wikipedia-Trustworthy-15597.shtml for a report about Wikipedia's accuracy.) Best of all, Wikipedia is a free service.
Microsoft's announcement concerning Encarta may be found at http://encarta.msn.com/guide_page_FAQ/FAQ.html.
Wikipedia can be found at http://www.wikipedia.org.