The “unofficial Apple weblog” had a post calling on readers to submit their wishlist for future iPhone OS features, which got me to thinking.

Multitasking is an obvious shortcoming on the iPhone right now. Multitasking is possible: some of Apple’s own apps run in the background, and there are jailbreak apps that allow apps to run in the background and for the user to switch between running apps. But Apple does not allow app-store apps to run in the background at all, presumably because of performance and battery-life problems.

I believe that multitasking on the iPhone can be broken down into two functional categories: apps that you want to run persistently in the background, and what I’m calling “interruptors”: brief tasks that only take a few seconds to complete, and where you don’t want to break out of your current app. I’m concerning myself with the latter case here.

A jailbreak Twitter app, qTweeter, has the kernel of an approach to presenting these interruptors: it pulls down from the top of the screen like a windowshade, and is accessible any time.

This approach could be generalized to present multiple apps in what I’m calling a pulldock. There could be one pulldock that pulls down from the top, another that pulls up from the bottom, to present up to eight interruptors.

I envision these interruptors being stripped-down interfaces to existing apps or services, such as twittering or text messaging, that would appear in some kind of HUD-like view superimposed over the running app. Interruptors should be lightweight enough that they wouldn’t overburden the phone. I can also imagine new ways of passing information between a regular app and an interruptor—such as launching a camera interruptor while in the mail app as a way to take a photo and insert it into a mail message, which would save a few steps.

Here’s a screencast:

Yeah, there’s a lot of “umms” and sniffing in there. It’s the first screencast I’ve ever done. The visuals were done in Keynote using the template from Mockapp.