Greenpeace and Chesapeake Climate activists hold banners for the Strike Out Exxon at Nationals Park campaign during a Nationals game against the New York Mets in Washington, D.C., September 15, 2008.

Greenpeace and Chesapeake Climate activists hold banners for the Strike Out Exxon at Nationals Park campaign during a Nationals game against the New York Mets in Washington, D.C., September 15, 2008. The campaign has been keeping the heat on the...

Greenpeace and Chesapeake Climate activists hold banners for the Strike Out Exxon at Nationals Park campaign during a Nationals game against the New York Mets in Washington, D.C., September 15, 2008.

Greenpeace and Chesapeake Climate activists hold banners for the Strike Out Exxon at Nationals Park campaign during a Nationals game against the New York Mets in Washington, D.C., September 15, 2008. The campaign has been keeping the heat on the...