open thread post here at C&L, NPR cited these reasons for their lack of coverage of the protests:

The recent protests on Wall Street did not involve large numbers of people, prominent people, a great disruption or an especially clear objective.

As Sam and Keith noted, with the arrival of Michael Moore, Susan Sarandon and Cornel West at the protests, there goes one of their excuses. And as they discussed, after the recent police brutality by the NYPD macing non-violent protesters, it appears the number of people coming out to protest has now gone up again.