Or, actually MP3 players in general:

• Some 11% of American adults say they own an iPod or other type of MP3 player. That amounts to over 22 million people.
• Men are more likely to have iPods/MP3 players than women. Some 13% of men have the players, compared to 9% of women.
• Minorities are more likely to own iPods/MP3 players than whites. Some 16% of African-Americans and English-speaking Latinos own iPods/MP3 players, compared to 9% of non-Latino whites.
• Almost one in five (19%) of those ages 18-28 have iPods/MP3 players. Fully 14% of those ages 29-40 have them; and 11% of younger Baby Boomers (ages 41-50) have them. That compares to 6% of older Baby Boomers (ages 51-59), 6% of those 60-69 and 1% of those 70 and older.

Also, more than 6 million Americans are listening to podcasts