Apple's come a long way from the insecure militant definsiveness that characterized the days of Guy Kawasaki's EvangeList mailing list. It's switcher campaign of several years ago was generally viewed as having mixed results. Apple put a human face on the Mac vs. PC debate, but the implication that those who hadn't made the switch were somehow still putting up with inferior technology left a bad taste in many PC users' mouths.
Apple's new commercials now personify the computers themselves. The "PC" (which looks a bit like a Bill Gates who's let himself go) is generally dressed in a suit or sport jacket while the "Mac" is an unapologetic, slightly scruffy hipster. The two generally seem to get along and even hold hands in one ad. Most derision of the PC is done as the kind of playful teasing that would occur between two friends. An iLife ad shows that iPods and iTunes can work with Windows, but doesn't make the case that they work better on a Mac (and they do, due to AppleScript and iLife integration).
In any case, the friendly ribbing approach works well for Apple to take in these days when its computers can run Windows and of course is well-timed as the company takes advantage of Windows Vista's delay. Vista would address several of the PC deficiencies addressed in the commercials.