Before we begin, leave your Apple hate at the door.
There are two reasons a company would move back to the US. They have direct monetary incentives (tax breaks, import costs, etc...), or they have indirect monetary incentives (Job creation, higher quality laborers, etc...). Any other reason is a direct link back to money.
Now, let's use that universal truth. The price of labor in China is rising. The price of labor in the United States has stagnated. Skilled labor in the US is maintaining costs, while skilled labor in China is difficult to find. The cost to import goods is rising, as fuel prices increase.
The question, that Apple seems to have answered for us, is "Does the move back to the US make sense?" A good accountant will measure current trends, and extrapolate how long it will take for large changes to make fiscal sense. No matter if you hate them or not, Apple runs a good business. They've obviously already done the math, and discovered $500 tablets sell better in countries that are willing to throw huge amounts of money at frivolous things. They made a business decision to open a plant in the US.
There is no reason to hate, or think that they are doing something just for PR. A company that can sell two year old hardware, with a decent OS, and make huge amounts of money is a success. Successes don't do stupid things, that require this level of planning, and remain a success. Apple shows no signs of deciding to become less successful...