RSS or really simple syndication has become a great tool to provide updates to a website subscriber. An RSS feed requires the web site to duplicate some content to be published as an XML file or feed, that a software running on the client (IE, Outlook or readers) downloads for consumption. RSS has become a great technology that showcases Software + Services model.
A Web Slice allows users to subscribe to a portion of a Web page. The Web Slice format consists of the minimum HTML annotations necessary to enable the publication and consumption of a mutable item on a Web page. Web publishers can use this format in to make portions of a Web page subscribe-able.
IE 8 is the software with the feature of consuming the web slice and show the slice and updates to the slice content in the favorites bar.
A great showcase of Software + Services implementation where a web site publisher can mark the content (web slice) which then is consumed and auto refreshed by the software (IE8) on the client.
To learn more about this new feature please visit http://msdn.microsoft.com/en-us/library/cc956158(VS.85).aspx
For all the new features in IE8 visit http://msdn.microsoft.com/en-us/ie/default.aspx