Apple has approved multitrack and is now in the state 'Processing for App Store', so it shouldn't be long before it reaches your device.
iTunes Store Link
Inter-App Audio - effects can be chained on each track, on the Bus return, and the Master out (*).
IAA Generators - on the Input to each track.
Audiobus 2.0 - Can be used as a sender for any track or master out. Supports saving and restoring state.
New graphics for iOS 7 - improved look is cleaner and less confusing.
Clean waveforms - rendered without blockies on retina displays.
64-bit support - with Neon optimizations and high resolution audio processing.
Dithering - applied automatically anywhere in the signal chain when bit width gets reduced.
Reduced filespace usage - up to 16 tracks before caches kick in on 64 bit devices.
Compressor - new dB reduction meter help you adjust threshold and ratio controls.
Completely rewritten audio engine - takes advantage of the best features of your hardware.
Supports up to 16 inputs simultaneously (USB hardware required).
Loop Points - changing loop points in realtime is now immediate.
Snapping - now you can snap to other regions, loop markers, and punch points, as well as Ruler lines.
Snap helpers - red vertical lines display exact snapping placement.
Song Menu - you can now drag song icons to reorder them.
IN Meter - now displays up to 8 input VU meters on iPad, or 4 on iPhone/iPod touch.
* IAA effects currently support only 1 instance at a time, system wide. In other words, you can't chain the same effect more than once.
