I am wondering because I feel like the Itouch for music plus that "Pedalbrain" application, mounted on my stem, would be pretty cool.
However, if I had to choose between Pedalbrain and music then it would not be pretty cool.
I've never owned an Iphone so I don't know. Could somebody please tell me?
If you are using the 'ipod' feature on the phone/touch, you can indeed have the music playing while you are using other apps.
If you jailbreak your phone, you can install an app through Cydia called, "Backgrounder" which will allow you to use apps like Pandora for music, while using your "Pedalbrain". The weakness of Backgrounder is if the phone/touch runs out of memory, it sends a signal to the app in the background shutting it off to make 'room'.
At this point multitasking on a iPhone requires "jailbreaking" the phone. However, this is much simpler than it used to be and is easily reversible. Google "blackra1n".
There is a lot of speculation that iPhone OS 4.0 will multitask.
However, I have both an iPhone and a Garmin 705 handlebar mounted for one reason: the iphone battery life with the GPS running is way to short. The Garmin is good for more hours than I can pedal in a day.