Fact is, a right-wing show can listen to 500 or so other right-wing shows for "message of the day" in addition to the blogosphere.
A left-wing show (or one that listens to l-wing issues, like Olbermann) has much less to fall back on concerning "message of the day" or "outrage of the day".
I guess my point is that the left-wing blogosphere is much more influential and crucial to their side right now, largely because there isn't anything else. Are right-wing blogs influential? Sure (particularly if you include Drudge, which I don't, b/c it ain't a blog). But certainly not indispensable or nearly as influential.
PS: The Air America article in today's WSJ is critical. Wonder why Drudge didn't link to it....