The next step for my Arduino-powered LC display is to move to a RaspberryPI instead – this has the main advantage that I won’t need a computer for receiving the http/json requests neither then using the Arduino wireless shield. Especially the wireless shield http library is not very stable for accepting incoming http requests – I think most of the people are using it the other way round.
For Raspberry, most of the developers are using Python to progam – even for GPIO there are several different libraries available so far. The most interesting one I have found is the q2w library:
I am preferring the C-method instead of learning Python; Gordon has provided a pretty good library called WiringPI to support basic Arduino-style C-development.