"Apple's iTunes continues to dominate digital music sales, gaining three percent compared to last year and comprising 66 percent of the market, according to news reports. Amazon, Apple's closest competitor, with just 13 percent of digital music purchases, tied Walmart, which relinquished first place to the Cupertino, Calif. firm in 2008."
Amazon has been trying to undercut iTunes, offering pretty steep discounts on their music but all it has gained them is about 2%, moving from 11% to 13%. Still a gain is a gain, however is the loss they are taking worth it? I admit I will shop at Amazon.com periodically and just use their handy MP3 Downloader to get the music into my iTunes library, but for the most part I will just stick with iTunes. It reminds me of the punchline in that old joke where the guy is selling sandwiches at a 25 cent loss: "Yea, but I make it up in volume."