The Chuck Todd Unit on MSNBC mentioned the "Barack Obama's not ready -- yet" line in the new McCain ad. Todd thought that "yet" was some sort of twisty esoteric McCain message implying four years of McCain, and then maybe eight years of Obama.
I don't think so. "Yet" is entirely about Palin. The McCain campaign hasn't been able to realistically make the experience argument because of Palin being, you know, ridiculously out of her depth. They can't say Obama isn't ready without saying that Palin isn't ready. So they needed the qualifier "yet."