Reply #11: 9-1-2007:

[Yossariant]

That's one reason why Clinton's campaign probably hesitated before signing the pledge.

The other is that Clinton's strategists disagree with the DNC about Florida's viability in the general election. Clinton's team believes she can win there; the DNC is more skeptical that Democrats can recover. Clinton doesn't want to give Republicans a heads-up there.
http://marcambinder.theatlantic.com/archives/2007/09/the_jockeying_behind_the_four.php

Mrs. Clinton’s advisers said it would be foolish to rebuff an important swing state, especially since doing so could alienate Democratic-leaning independents who could be favoring her. But she is also taking a risk that staying in Michigan will not hurt her in Iowa, New Hampshire, Nevada and South Carolina. Those states, all sanctioned by the Democratic National Committee to vote first, forced the Democratic candidates to sign a pledge not to campaign in Michigan and Florida. Clinton advisers said that even though she was staying in the Michigan race, she would not campaign there.
http://www.nytimes.com/2007/10/10/us/politics/10michigan.html?_r=2&partner=rssnyt&emc=rss&pagewanted=all&oref=slogin&oref=slogin