Tomfors has released 4 new emulators for the iPhone

Heres what systems are emulated:

HP-11C Scientific Programmable Calculator for iPhone.
HP-12C Financial Programmable Calculator for iPhone.
HP-15C Advanced Scientific Programmable Calculator for iPhone.
HP-16C Computer Scientist Programmable Calculator for iPhone.

http://code.google.com/p/hpcalc-iphone/