So, was John Gruber right? This is what I found while browsing the new iTunes Store (cool stuff, btw!):
User-Agent: iTunes/9.0 (Macintosh; Intel Mac OS X 10.5.8) AppleWebKit/531.9
Survey says: Yes.
It’s important to understand that iTunes is only using WebKit to render the iTunes Store and iTunes LP. The rest of the iTunes UI still remains native in Carbon.
Previous versions of iTunes had a custom native UI for viewing the iTunes Store and were definitely not WebKit based prior to iTunes 9.