Blackout Labs has released i808 (App Store link), a Roland TR-808 style drum machine for the iPhone.

Description:

Make beats with 11 timeless drum machine instruments used in today’s rap, hip hop, R&B, and techno/electronica songs.

Change patterns, add instruments, and configure options on the fly as you listen to your beat.

i808 is built with extreme accuracy making it a reliable drum sequencer and an excellent metronome. Instructions: Each pattern is divided into 16 beats.

To play an instrument on a beat, select that instrument and press the beat buttons you desire that instrument to play on. Press play to hear your beat.

Edit your patterns, beats, and instrument options in real time while playing or while stopped. Hold down a pattern button for 3 seconds to clear it. Use the accent to add dynamics, making some beats louder or softer than others. To change the tempo, press stop if playing, click the tempo box, and type in the tempo you want. Your patterns are automatically saved when you close i808. Tips: -Patterns change as you lift your finger. To change on a precise beat, hold the pattern button a few beats before you want to change and then release on the beat you want.

For the best sound quality, use the iPhone or iPod volume control. If you desire further volume increase, use the “Total Gain” slider in the options screen. i808 samples are authorized for use in both commercial and non-commercial music compositions only.