Is iPhone OS 3.0 a boon for the accessory market?

At Tuesday's iPhone OS 3.0 preview event, Apple unveiled several new features of the iPhone operating system, including the capability to create applications specifically for interfacing with third-party hardware. Examples given included a five-band EQ interface for speaker docks, or an FM transmitter control that allows you to select broadcast frequencies based on signal strength.

An example of the Alesis ProTrack using an application front end for recording control.

This may sound like a benign little announcement to most people, but as someone who closely monitors trends in iPod accessories, I expect that this will be huge for the industry. What company isn't going to want to differentiate its products with a slick app?

I expect that everything from battery chargers to stereo Bluetooth headsets will (for better or worse) be given the app treatment. The products won't necessarily be any better for it, but the gee-whiz appeal alone will probably carry manufacturers and consumers through to the end of the year.

The nightmare for me is going to be all the apps I'll need to download for each iPod and iPhone accessory I review. Every speaker and every dock will likely require an app download to get the full picture of the product. Version updates for apps will also be a pain. If Altec Lansing hypothetically updates the EQ control on the app for its latest line of speakers, suddenly, I'll need to add a note to all its product pages.

But there are some potentially cool things to come out of hardware-specific applications. Here's what I'm looking forward to seeing:

Buttonless products. Call it the "Shuffle Effect," but if you can migrate all of a product's controls to the iPhone's touch-screen interface, then why have buttons? I'm not saying it's a good idea, necessarily, but the potential makes it inevitable that we'll see a product like this sooner or later.

Game controllers. Maybe it's just me, but I get a little giddy from the idea of plugging a reproduction of the vintage NES controller into the dock of the iPod Touch to play a little old-school Super Mario. Not every game is suited to touch screen and accelerometer controls.

Audio recorders. Companies like Alesis have already been trying to accomplish app control of hardware by advertising its product's compatibility with Bias' iProRecorder application. It's not a perfect marriage, though. The iPhone/iPod Touch behaves like a recording medium, while the settings for the recording hardware are still strictly controlled by buttons and switches. Really fine-grain control over gain settings, compressor ratios, gating, panning, surround effects, and audio editing are much better handled on the screen than with hardware, allowing the expression of greater complexity and unique graphical controls.

Nike+iPod alternatives. The Nike+iPod exercise kit is a very cool way to track your progress with running and jogging, but you've got to buy special Nike shoes and the proprietary Nike pedometer puck, and the software isn't for everyone. I know Apple and Nike are closely partnered on the Nike+iPod product, but I could see something come along that doesn't compete directly and works more like the Wii Fit, with it's own hardware and application.

I'm sure there's way more potential here than I can come up with. Personally, I would love to see some hardware for enhancing the portable music-listening experience on the iPhone with EQ or music sharing, but I'm not sure how you would pull it off without being able to run applications in the background.

[Correction: It appears that apps in OS 3.0 will now be able to access and play music files stored on the iPhone and iPod Touch.]

What do you think? Are there any hardware-dependent apps that could make your iPod/iPhone accessories better or more interesting?