You may not see it yet, but SrutiBox is poised to go on sale in the app store. I was actually using it myself to get some calm in my life and stop being in my head so much.
I'll come up with that public video and sound samples, I guess.

Meanwhile, TiltSynth is also shaping up as the next app in line, I'm thinking of changing its synth engine to one more like Sruti's.
There's already an OSC client out there for the iPhone, OSCemote, with a lite version that's free. Also there is mrmr, which is a very interesting OSC controller project that lets you configure the interface via OSC and discover it via Bonjour (zeroconf). But neither of them sport native synth - I think.

In fact, I'm thinking of a lot of things. The engine of the internet Synthesizer (circa 1995) is not too bad, and the synth engine behind Buzz, my Amiga-based sound server might be OK here too. I could also do a version of RGS, which would be easy and fin to do, and other ancient Amiga JForth programs, like the one that breaks up audio into zero-crossing loops and lets you skim over them to play them. There's also LYR from the old Amiga days, which might not adapt well, since it needs the keyboard to act as autoharp buttons.

And then, there are a lot of other things, not audio related, that I'm working on.