A couple of small--but I think somewhat serious--issues regarding the audio output of the iPhone have been percolating on the Web for the last week or so. The issues involve the iPhone's headphone/headset jack and the phone's ability to output stereo sound via Bluetooth.
Let's start with the headphone jack. In Walt Mossberg and Katherine Boehret's iPhone review for the Wall Street Journal, they state, "The headphone jack, which supports both stereo music and phone calls, is deeply recessed, so you may need an adapter for existing headphones." Why the port would be so deeply recessed is a mystery, but in case you missed it, the folks over at iLounge had a blurb on a $11 Belkin iPhone adapter the other week to deal with the issue. Who wants an adapter protruding from the side of your cell phone just so you can use that pair of good earbuds you already own?
On the Bluetooth front, rumors that the phone would not support stereo Bluetooth streaming popped up around the Web as soon as it was revealed that there was no A2DP support, but it's now been confirmed that the iPhone only offers mono Bluetooth audio output (essentially for headset use). This means you won't be able to wirelessly stream tunes from the iPhone to one of the many new and improving Bluetooth stereo headphones or Bluetooth speakers. Fans of the cordless headphone concept (I am one) should be a little upset over this because most so-called multimedia phones offer stereo Bluetooth audio output.
At this point, it's unclear whether Apple will be able to add stereo Bluetooth output to this generation of iPhone, but I certainly hope it does soon, especially as many folks are speculating that next-generation iPods will have some sort of wireless streaming feature built into it.