The headphones that came with your iPhone also let you control music playback from the button on the microphone.
Music (built-in app)
Submitted by SolomOn27 on Wed, 10/01/2008 - 11:31
There are a number of ways you can control the playback of your music from the Now Playing screen on your iPhone or iPod touch. To display the Now Playing screen, tap the Now Playing button in the upper right corner of the screen, and then tap once anywhere on the album art. This will open a screen giving you three options:
Submitted by Anonymous on Wed, 10/01/2008 - 11:23
When you first add music to your iPhone or iPod touch in iTunes, it will automatically add a playlist called On-The-Go. You can add music to this playlist at any time, even when you are not connected to iTunes. Here’s how: