Just approved last night:
From AppNoose the ITGO Interval Trainer.
ITGO – Interval Trainer GO – is a dedicated interval signaling App for the iPhone and iPod Touch specifically designed to offer advanced user controlled signaling in the form of vibration, sound and visual alerts while playing user defined, App-specific fast/slow interval song playlists.
I’m really pleased and proud of how the UI turned out on this app. The knobs especially.