Jacqui Cheng has a visual history of all the major versions of iTunes (brushed metal represent):
We’re still waiting for the newest version of iTunes, which Apple introduced in September during its iPhone 5 media event. The makeover, which will undoubtedly end up as version 11.0 (though Apple isn’t publicly referring to it as such), consists of a “dramatically simplified new interface,” better iCloud integration, a revamped mini-player, and Facebook integration.
In all I’ve read about the new version of iTunes, I’ve never noticed that Apple hasn’t ever referred to it as “iTunes 11”. Interesting.