During the lecture, during the second day of the conference Professional Developer Conference (PDC) in Los Angeles, Microsoft has announced the fourth version of the Silverlight browser plug-ins. The first beta version of Silverlight have 4 you can download and test yourself. How informed Scott Guthrie, who is vice president at Microsoft NET Developer Platform team, technical progress in the new version takes place on three fields: handling the media, applications to business processes and changes in the functioning of Silverlight, so that it acted properly regardless of browser.