There's a mobile-ready web interface that's not quite finished, but if you'd like to try it just visit https://your.tapchat:8067/chat in your phone's browser.

One of the contributors to the znc project is working on an iPhone app, currently in private beta. Register your interest at: http://palaverapp.com/

What do you find lacking in your znc + colloquy? Mine works pretty well. Plus, no one else has push highlights...