I have been learning about how to program and make beginner projects on my arduino mega adk for about a year now. In the last month I have made my first project controlling a tank track rc car with a play station controller. That is not the reason for my post tho. My reason for this post is that I am writing it from my cell phone.
I read posts that people write that show what they used their arduino for on my cell phone. I read about new arduino products on my cell phone. I shop for shields and components for my arduino on my cell phone. As you can see I do allot on my cell phone. The only reason I sit down at my desktop computer is to download a library and program my arduino. My thought is why do I have to detach myself from the world in my basement away from my family and friends to enjoy my hobby. My solution to this is a smart shield. An addition to the arduino shields that we already use but know what pins they use and are preprogrammed. They act like a USB camera that I plug into my computer. This is only an idea. I do not know how to make this happen or even if it is cost effective.
I do not know how to make this happen or even if it is cost effective.
Let's assume that there is a shield that the phone can communicate with. Have you installed the Arduino IDE and gcc toolchain on your phone? Can you even compile and link a sketch on your phone?
Now, lets suppose that you get over that hurdle. You need to get the hex file from the phone to the shield. What mechanisms are there for getting data from your phone to another device, like a PC? Bluetooth? USB cable? Are any of those mechanisms available as shields? USB is, if you have a USB Host shield and you write a driver. That's a pretty significant piece of code.
The mega adk has basically a USB shield built in . The board cost me about 60 dollars. From what I understand is that it is a google deal. I do not think it is a new idea or that hard to program from an android phone. The new arduino zero says it has a virtual com port that can be used for programming and traditional bootloader functionality. So can a shield with an sd card or some other memory be put on a zero and at the push of a button be transferred to the zero to run. So say I have a robot or some machinery and no computer other than the phone in my pocket and the zero in the robot or machine and want to change the way it works I just change the code maybe someone sends me new code. I put it on the card and put it in and then it can run that. Without the need to have a computer.
From what I understand is that it is a google deal.
No idea what this means.
I do not think it is a new idea or that hard to program from an android phone.
Android phones are not the only smart phones.
The google deal and arduino mega adk can be read about here Google's Arduino-based ADK powers robots, home gardens and giant Labyrinth (video) | Engadget .
Yes there are many different types of smartphone and operating systems. I personally like my iPhone and do not have a phone that runs android or windows which I believe are the three most popular.
The Arduino developers already struggle with keeping the Arduino IDE current on Windows/Linux/Mac, adding another platform to support the IDE & tool chain seems a bridge too far to me. But if a 3rd party wants to take a try at it, all the power to them. When they prove out the concept then maybe the Arduino developers could take a look at it. I would rather hate to have to write a sketch on a small smart phone screen, but maybe others would?
The OP here has indicated a very important trend.
The current middle-aged generations are accustomed to the PC being the key resource and the phone as being supplemental to that. But the younger generation see their phone as being everything, and computers as old-fashioned.
Real Programmers don't program on smartphones. 
Can't do hardware design on a smartphone either.
Face it, they're just a communication toy, and you can browse websites on it.
On second thought, it could be made to work, there's plenty of screen space for this:
LOL, that's awesome Jack!
Or on machines that run Windows....
Guess I'm not a real programmer then!
Oh wait, I say that all the time. I just play one here 8)