Twitter's new logoFour of the five most-shared news links via Twitter were very close to home, involving social media and Twitter itself, while the war in Afghanistan and the death of actor Kevin McCarthy tied for the top spot on the list of news links shared by bloggers, and the most-watched news and politics video on YouTube was a since-removed ad for Newsday‘s iPad app, according to the Pew Research Center’s Project for Excellence in Journalism’s New Media Index for the week of Sept. 13-17.

The most-Tweeted link was an item from Wired‘s Epicenter blog about Twitter’s redesigned home page, accounting for 15 percent of links shared via the 140-character service. It was followed by: a Mashable post about upcoming social-media site Google Me, at 11 percent; another Mashable story about Facebook Places going live in the United Kingdom, at 10 percent; the one non-tech offering, a BBC article about a British sportscaster’s complaint that a TV show made an inappropriate comment about her sexual identity, at 9 percent; and Bitbop, a new Android app that can bring streaming TV shows to smart-phone users over 3G or Wi-Fi, at 6 percent.

No single topic captured the imagination of the blogosphere, as Afghanistan and McCarthy each accounted for 13 percent of shared news links, followed by: a 2004 BBC article about the discovery of a diamond star that astronomers named Lucy, at 11 percent; two Washington Post opinion pieces about the war on terror, at 10 percent; and a story in the Los Angeles Times about President Barack Obama‘s crumbling electoral coalition, at 9 percent.

The erstwhile Newsday ad was followed on the list of most-viewed YouTube news and politics videos by: a view from a home in San Bruno, Calif., of a fire caused by a ruptured natural-gas line; an episode of The Philip DeFranco Show; another DeFranco show, Fail Friday; and New Jersey Gov. Chris Christie responding to a question from a teacher at a town-hall meeting.