Belkin products have announced the sale of the Dock Adapter for iPod Shuffle. According to their website this is what they have to say about it:?

This essential add-on for the iPod shuffle lets you connect iPod accessories with the Dock Connector through the shuffle's USB port. The Dock Adapter for iPod shuffle gives your shuffle the flexibility to work with such enhancements for iPod as battery packs, mobile power cords, iPod speakers, and USB/FireWire cables that have the Dock Connector.

Note:Requires 5V+ of USB power to charge your iPod shuffle. Compatible with power and audio accessories only. iPod photo accessories and car integration kits are not compatible with the Dock Adapter for iPod shuffle.

*Will not sync when used with a FireWire cable. However, power and audio will be compatible.

Operating Instructions:iPod shuffle must be in the ON position (in either shuffle or play-in-order mode) to charge when used with the included AC or DC adapter.

Advantages:

Charges your shuffle using your Dock Connector's power cord
Works with any Belkin TuneBase
Provides pass-through audio