From a Pew Research Center's Project for Excellence in Journalism study on how selected U.S. MSM print and media outlets use twitter:
Kady O'Malley does pretty frequently--crowd sourcing her news gathering--seems to be quite rare in U.S. journalism:
Of the 13 most heavily followed individuals at the news organizations in the study, the average number of tweets in a week was 32, or five times per day.
When these journalists did tweet, very little of that material was information-gathering in nature. Eight of the 13 reporters examined never asked followers to help provide information. On average, only 3% of individual reporters' tweets did so.
Other findings, for instance that a outlet's main twitter feed acts mostly to drive traffic to the outlet website, are less surprising.
Here's another neat study the Center just over a year ago on blogging and the MSM.
PS. Nowhere in the study does it say the twitterverse skews left; that's just my interpretation of a couple of their graphs.