MobileSynth is free, an open source synthesizer, targeted initially for the iphone.

2011-10-06: Discussion of projects that use code from mobilesynth

2010-09-02: Mobeat Synthesizer includes code from mobilesynth.

2010-07-06: mobilesynth featured in iTronic.

2010-07-02: olsynth for iPad launched, based on some mobilesynth code.

2009-12-10: mobilesynth is back in the app store thanks to ECSOS.

2009-11-15: Another synthesizer that uses mobilesynth code. Awesome. Check out Moogie Synth.

2009-10-25: I didn't renew my Apple developer membership. ($99 for distributing a free app, ugh). Let me know if you're interested in distributing this app.

2009-10-11: I wish I had seen this earlier -- mobilesynth code used in a great iphone synthesizer, GravSynth.

2009-06-01: mobilesynth featured on ~Ore~. Have a listen at I, Phone.

2009-03-21: Stats from the iTunes store
Below is a graph of mobilesynth's download rate from the iTunes App Store over the last 16 days:

I have checked in the raw data here, if you are curious. Notablty, nearly 50% of all downloads are from Japan

2009-03-06: You can find mobilesynth in the iTunes App Store.

2008-12-21: Screenshot