The most interesting commentaries I've found about the Obama speech among today's online postings:

Harold Myerson's "Obama Goes Beyond Oratory" for the American Prospect (Obama will win "by being the kind of Democrat they remember with fondness. By being Harry Truman").

John Heileman's "Seven Ways Obama's Speech Succeeded, and Why It Wasn't Perfect," for New York Magazine.

David Gergen's "A Political Masterpiece," on cnn.com.

Among the most interesting commentaries on the McCain choice of Palin:

Ed Rollins' "Palin Is Brilliant, but Risky, VP Choice," on cnn.com

Paul Begala's "Is McCain Out of His Mind?" on cnn.com

William Greider's analysis, "McCain's Hail Mary Pass," for the Nation ("The Senator was widely thought to be on the fifty-yard line, nose to nose with Barack Obama. But this selection reveals the Republican campaign strategists knew better. Picking the obscure and under-experienced governor from Alaska for veep means McCain and his people recognize they are in a very weak position for the fall campaign. So weak they decided to throw a forty-year Hail Mary pass and hope audaciously for a lucky catch."

Rebecca Traister's "Should Obama Have Picked Hillary?" on salon.com.

John Dickerson's blog, "McCain's New Palin," on slate.com: "Palin is famously pro-life and will only solidify McCain's hold on his base. But Palin also helps McCain make a run at those moderate voters for whom McCain's conservatism (and particularly his pro-life views) is not a deal breaker. As one McCain aide put it: ‘We either get Hillary's voters and we win, or we don't. It's not a mystery.'