Instead of writing something that others will link to, I will link to something that others wrote

Slate has an interesting article about a rhetorical device that's being used a lot this presidential campaign season, by pretty much all the major politicians:

Politicians eager to keep up with the latest fad need more than a flag pin this election season; the hottest accessory of the 2008 campaign is the reversible raincoat. That's the nickname speechwriters have given to the rhetorical device in which words are repeated in transposed order, as with Churchill's famous line: "Let us preach what we practice—let us practice what we preach." The fancy Greek name for the trick is antimetabole, and it's been cropping up in speeches by Democrats and Republicans alike.