Liberal activists cheered Massachusetts Sen. Elizabeth Warren's electrifying keynote speech at Netroots Nation this summer with chants of "Run, Liz, run!" There's even a Ready for Warren super PAC, formed in July with the mission of encouraging the senator to mount a presidential bid. But the longtime thorn in the side of Wall Street has insisted that she's not running, and even took the unusual step of formally disavowing Ready for Warren in August.