I figured this out myself. You will need to have a device that supports A2DP (Advanced Audio Distribution Profile), with this you can connect your phone or iPod Touch to the car kit as a music device and playback music without needing a cable.

Description of A2DP from Wikipedia:

This profile defines how high quality audio (stereo or mono) can be streamed from one device to another over a Bluetooth connection. For example, music can be streamed from a mobile phone to a wireless headset or car audio or from a laptop/desktop to a wireless headset.

A2DP was initially used in conjunction with an intermediate Bluetooth transceiver that connects to a standard audio output jack, encodes the incoming audio to a Bluetooth-friendly format, and sends the signal wirelessly to Bluetooth headphones that decode and play the audio. Bluetooth headphones, especially the more advanced models, often come with a microphone and support for the Headset (HSP), Hands-Free (HFP) and Audio/Video Remote Control (AVRCP) profiles.

A2DP is designed to transfer a uni-directional 2-channel stereo audio stream, like music from an MP3 player, to a headset or car radio. This profile relies on AVDTP and GAVDP. It includes mandatory support for the low complexity SBC codec (not to be confused with Bluetooth's voice-signal codecs such as CVSDM), and supports optionally: MPEG-1 , MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs, such as apt-X. Some Bluetooth stacks enforce the SCMS-T digital rights management (DRM) scheme. In these cases, it is impossible to connect certain A2DP headphones for high quality audio.