Multinational oil giant Shell has agreed to pay nearly $5 billion for privately-held East Resources to "give it access to a swathe of the Marcellus Shale, the northeastern U.S. rock formation that is one of the crucial sources of future U.S. gas producti on." Follows Exxon's move to boost its Marcellus assets in Pennsylvania and other Appalachian states earlier this year. Reuters story here.