This policy setting controls whether Outlook subscribes to the Common Feed List, which is made available to multiple RSS ...

This policy setting controls whether Outlook subscribes to the Common Feed List, which is made available to multiple RSS clients. The Common Feed List is a hierarchical set of RSS Feeds to which clients such as Outlook, the Feeds list in Internet Explorer 7, and the Feed Headlines Sidebar gadget in Windows Vista can subscribe. 

If you enable this policy setting, Outlook automatically subscribes to RSS Feeds added in Internet Explorer, and Outlook RSS Feeds are synchronized with the Common Feed List so they are available in Internet Explorer. Be aware that third-party applications besides Internet Explorer can add RSS Feeds to the Common Feed List, and if you enable this setting Outlook automatically subscribes to those RSS Feeds as well. 

If you disable or do not configure this policy setting, Outlook maintains its own list of RSS Feeds and does not automatically subscribe to RSS Feeds that are added to the Common Feed List.