Krugman has been listed as a JournoList member on several compilation lists floating around the web, and a post from one member  seems to confirm it:
Over time, the group grew to about 400 people. I was one of them. It was basically a place to shoot the breeze about things such people find interesting - politics, policy, sports, music, themselves. You'd probably recognize a few of the participants like Paul Krugman, Katha Pollitt, Jeffrey Toobin, and Joe Klein, but most of them were pretty obscure, i.e. people like me.
Times Watch has long suspected Krugman was getting his talking points straight from left-wing blogs; it turns out they were being pumped directly into his inbox via JournoList.
On June 12, 2009, Times Watch described Krugman's modus operandi : "Parrot the left-wing blog argument of the day in slightly varnished form..." In a blurb for a November 16, 2009 post, Times Watch called Krugman an "economist turned liberal-meme chasing columnist." And a blurb for a March 23, 2010 post  advertised Krugman's "latest talking points culled from the left-wing blogosphere."
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