With Internet Explorer 8 users are able to run multiple instances of the browser, completely separate, each in its own session. With the latest release of the Internet Explorer, the Redmond company aimed to simplify browser session handling, simplification which allows IER8 to move away from the traditional model of “session merging.” In this context, users will notice that IE8 comes to the table with an extra option in the File menu dialog in addition to New Window, New Tab, or Duplicate Tab. It's called New Session, and when clicked it opens up a new window of IE8 that shares no cookies with the source window.
“Simply click the New Session item on the File menu, and a new browser window will open. The new browser window will not share session cookies with the original browser window, so you can log into Hotmail (and most web applications) as a different user. For command line junkies, you can run iexplore.exe with the -nomerge parameter,” explained Eric Lawrence, a security program manager on the IE team.
The same is not valid for the New Window, New Tab, or Duplicate Tab actions. At the same time, opening multiple instances of IE8 from the browser's shortcuts in various areas of the operating system will also be made under the umbrella of session merging. Only when New Session is used does the new window opened not have any cookies in common with the rest of IE8.
“Proper support for Session Merging is important because most web applications are written to expect it. For instance, when a web application opens a popup window, it usually does so with the expectation that the popup window will share cookies with the main window, so that the user will remain logged in and their preferences will remain available, etc. Similarly, when the user uses the Duplicate Tab command, they reasonably expect the new tab to show them the same content as the original tab – sharing cookies is critical for that scenario to work correctly,” Lawrence explained.
Internet Explorer 8 (IE8) RTW is available for download here (for 32-bit and 64-bit flavors of Windows XP, Windows Vista, Windows Server 2003 and Windows Server 2008).