TechCrunch had excellent CES coverage, including interviews and demos with two MIDI Guitar controllers coming out this year.
Zivix has stripped down a guitar to the basic essentials in the JamStik. Real strings and some neat sensors detect your precise finger placement on the fretboard, allowing for extremely accurate MIDI notes while playing.
Zivix has some previous experience in this realm, with JustJam and Peavy JamParty Mix rhythm video games. They will be including their own iOS app JamMix, but the JamStik should work with any app that supports CoreMIDI.
JamStik should be available this Summer for around $300.
In this video TechCrunch's John Biggs sits down with Chris Heille and Chad Koehle to hear it in action. You might also want to check out Zivix's own promo video, which goes into great detail: What's a Jam Stick?
Artiphon Multi-Instrument 1
Artiphon is offering a vastly more expensive wooden guitar controller with a slot to plug in your iPhone. At $800, and in limited production runs, this could easily be the most flashy instrument peripheral for the iPhone.
Instead of the JamStik guitar strings, the Multi-Instrument 1 is using "force-sensitive" virtual strings. This allows for it to be played in a variety of styles; including guitar, bass, violin, banjo, or drumpad.
In this video TechCrunch talks with Artiphon founder Mike Butera, who does a good job of demonstrating the different playing styles. He hasn't talked me out of $800, but it is a good effort!