Massachusetts Republican Scott Brown officially becomes a U.S. Senator today, when he's sworn in by Vice President Joe Biden. Brown will be the 41st Senate vote for Republicans, which is enough to block President Obama's agenda. We speak with Rick Klein Senior Political Reporter for ABC News and author of the ABC political blog “The Note.”

The U.S. Transportation Department has opened an investigation into brake problems in Toyota's Prius. We talk cars with Ray Magliozzi, half of the Click and Clack team, on NPR''s Car Talk.

It's one of the most successful experiments on the web. There are now Wikipedias in about 250 languages, while the English version has grown to 25 times the size of the the Encyclopedia Britannica. But articles are skewed toward popular culture and the growth of entries has slowed, amid controversies about the site's rules. So how can Wikipedia keep growing? We speak with Evgeny Morozov, contributing editor to Foreign Policy Magazine, where he also runs the "Net Effect" blog.

For centuries, lovers have put pen to paper to express their feelings. But the course of romantic correspondence doesn't always run smoothly. We talk about epistolary affection with Thomas Mallon, author of "Yours Ever: People and Their Letters."
http://blogs.cars.com/kickingtires/toyota-recall/

• Kar-Kar Madison, "Boubacar Traore"
• Charles Mingus, "Boogie Stop Shuffle"
• Moby, "Inside"
• Film School, "P.S."
• Thelonius Monk, "Caravan"
• Massive Attack, "Future Proof"
• Paul Simon, "50 Ways to Leave Your Lover"
• Gustav Holst “The Planets, Op. 32: Saturn, the Bringer of Old Age” performed by the London Symphony Orchestra and Sir Colin Davis