In iTunes 7, there was a preference to disable the links to the iTunes Store -- these are the small arrows that appear when you select a song in your library. In iTunes 8, however, that preference is gone. A bit of digging in the iTunes' binary found the solution, thankfully.
If you'd like to disable the iTunes Store link arrows, quit iTunes, open Terminal, and run this command:
Relaunch iTunes, and voila, no more arrows! To reverse this behavior, you can repeat the above command (quit iTunes first), but replace FALSE with TRUE. (Or, if you prefer, you can completely delete the added preference with defaults delete com.apple.iTunes show-store-arrow-links).
defaults write com.apple.iTunes show-store-arrow-links -bool FALSE
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