A Google employee has recently said that search engines have improved so much that people are surprised when they don't get good results. When Google has been launched, users were really surprised to see relevant results, even if they were much poorer than they are today.
When you search for [iPod], you expect that the first result is iPod's homepage. Google returns a different page (iTunes homepage) and doesn't even include the iPod homepage in the list of the top 10 search results.
Bing and Yahoo Search return much better results: iPod's homepage is the top result in Bing and the second result in Yahoo Search.
The most likely explanation why Google doesn't return the most relevant results is that apple.com/ipod used to redirect to apple.com/itunes, as you can see if you check Internet Archive. The most recent version of the page cached by the Internet Archive is from October 2009 and it still redirected to the iTunes homepage.