There is a new music app available in the App Store since today, called Rockmate. Rockmate turns your iPad into a complete music studio easy and super fun to use. You can compose, record and play songs with up to 4 Rock players on one single iPad. Rockmate is easy to play with smart chords progressions, sounds great with separated guitar effects and in-house produced audio samples and is also fully customizable with multiple drums and keyboard styles. » Rockmate For iPad: Whole Music Studio In One App

I already informed you of the upcoming Moocow Music band app here.

Well i have some extra news for you.
The app is so powerfull that some beta-testers have started to create there own music instruments and i must say, they are looking very well.
It seems that this app has no limits if you look at what those guys already made.
» MoocowMusic band extra instruments

We’ve had all sorts of music devices being emulated by our iPhone and iPod Touches.
For the people who are new on iPhoneFreakz, check out the iBand video here.

The guys from MoocowMusic are testing the final beta of an application that will combine almost all of the previous devices into 1.

It will include a piano, guitar, drummer, scratch-table and much more.
» MooCowMusic a full band in your iPhone