The second GuitarJack incarnation, Model 2, is now with us and it's compatible with iPhone, iPad and iPod touch - connecting via the dock port.
GuitarJack will take a guitar plugged into its standard jack input and also has a mini jack stereo mic/line input so you can record in stereo and simultaneously record vocals and an instrument when used with an app that supports that function such as Sonoma's FourTrack multitracker (£6.99), which includes a GuitarJack control panel to set the 1/4-inch jack input impedance, various parameters for the mini jack, plus input gain levels.
GuitarJack is ruggedly built and offers a great sound quality plus a robust headphone output for plenty of volume. We were able to use it with guitar straight out of the box with GarageBand and other amp sim apps as the default setting for the standard jack input is for Hi-Z with a decent level of input gain.
You get two free apps included in the GuitarJack package: GuitarTone offers amps and effects simulation while Taylor EQ provides a variety of presets based on Taylor guitar shapes. These can also be used as plug-ins in FourTrack so you can record full electric guitar tones and add character to an acoustic.