iTunes 10 has a new social network built in, but sadly there’s not an easy way to just disable the whole thing entirely—you’ll need to resort to a command-line hack to get it done.
Just open up a command prompt and switch to your iTunes installation folder underneath the Program Files directory, and then run the following command:
iTunes.exe /setPrefInt hide-ping-dropdown 1
That’s all there is to it. Hit the link for the instructions for Mac users.
How to Hide the Ping Drop-Down in iTunes [Lifehacker]