Last year, an audio-enabled version of HP's Touchstone wireless charging dock appeared on eBay with a discontinued Pre 3. With HP taking a step back from webOS, this review from webOS Nation is as close as most of us will ever get to the unannounced and never-sold Touchstone 2 Audio Dock. Based on what they've found, that's not exactly a tragedy. "For every 'we like this,'" they write, "the Touchstone 2 throws a roadblock up in our way of giving it a stamp of approval."
The Touchstone 2 offered the inductive charging of the original dock, but added a Bluetooth receiver and audio out jack. When a Pre 3 and a set of speakers were connected, the Bluetooth turned on and paired with the phone automatically, streaming music to the speaker. This pairing apparently works very well, but audio quality suffers. Worse, the industrial design doesn't live up to the original Touchstone: the Touchstone 2 is both larger and lighter, so it takes up more space but has a tendency to get carried away when you pick up the phone. If only to satisfy your own curiosity, it's worth reading the full review to see what might have been at HP.