According to TLA, the most significant new feature in PCalc for iPhone is support for multiple undo and redo. The feature can be envoked by swiping your finger to the left and right on the iPhone’s display.
You can now also change the color of your screen to simulate the old red LED calculator. Layout improvements and an HP style RPN are also new with this version.
PCalc 3.3 for Mac OS X will be available in the next month, incorporating all of the improvements made in the iPhone version and a new look. PCalc 3.3 will be a free upgrade for existing registered users.