chatter:feed Displays the Chatter EntityFeed for a record or an UserProfileFeed for a user
Chatter components are unavailable for Visualforce pages on Force.com sites. Ext JS versions less than 3 should not be included on pages that use this component. Note also that the chatter:feed component doesn't support feedItemType when the EntityId entity is a user. Use SOQL to filter on the UserProfileFeed object's Type field instead.