Users with iOS 5 can now purchase text and alert tones directly from the iTunes store. While Apple has sold ringtones for a while now, this is the first time alert tones have become available.
Located on both the iPhone/iPod touch and iPad under Settings > Sounds > Buy More Tones, tones are available from within three main categories. These include Dialogue, Music and Sound Effects.
Once purchased, these tones are automatically installed within iOS. The new alert tones are $.99 vs. $1.29 for ringtones.