I'm not sure if I've discovered a hidden feature on the iPhone but as of this morning dot wav files embedded in iPhone Mail can be played. I currently use Vonage for my home phone service and anytime someone leaves a voicemail Vonage sends my wife and I an e-mail with their message embedded as a dot wave file.
We've had this set up ever since moving to Vonage over a year ago. Until today I would listen to the wav files in Apple Mail on my Macbook Pro. Always the optimist I'd click the wav file in all voicemail e-mails but would consistently be met with the message: "This audio type is not supported."
This started working today and the app that plays the wav files looks very much like QuickTime. Here are some screenshots showing the e-mails in iPhone Mail and what results when clicking on them. Anyone seen anything like this before?
Voicemail Notification E-Mail from Vonage

Listening to the WAV File Voicemail















It's quite nice actually.