The National Review Editors say it well:
By picking Alaska governor Sarah Palin as his running mate, John McCain has wowed the public and enthused the Right. He has reinforced some of his winning themes — that he has the mindset of an outsider and a fighter against corruption. He has also reinforced his appeal as the candidate more in touch with traditional values on moral issues.
They go on to note that the Palin selection means that McCain must carry more of the foreign policy load. (Just fine, IMHO, given that he is particularly passionate about those matters.) Another great line:
“They (McCain – Palin) should not accept the portrait of middle-class Americans as hapless victims that so many of the Democratic speakers this week portrayed; but they need to show that they share middle-class frustrations.”
This is super-important, given that Obama/Biden have aimed squarely at portraying McCain as out of touch with people’s needs. Read the whole (short) piece.