It's coming!
I'm already starting to see this, but it's in dribs and drags. The biggest holdup is the UI, it's tough to make a UI suitable for programming but that also works on a touch screen. I have an IDE on my WP7 phone, it's from Microsoft and they have some very advanced samples written in it (like a "Missile Command" clone), and I've written some basic, fun apps in a few minutes (like one that gets the current location from GPS and posts a map to get to my location to Facebook... easy way to say, "hey, here's the place I told folks to meet me at!").
I think the process is going to be slow, but the number of folks who are interested in programming mobile apps is high... tons of interest from people who wouldn't give development a second thought before. While the vision of doing it directly on the device isn't there very well or in depth, people *are* doing a lot more customization via code, and as things like docking stations make getting "real work" done on the form factors easier, I think you'll see more direct, on-device work getting done too.
J.Ja
