As with any product made by Apple, the iPhone’s interface and overall user experience could be improved in a few areas. Ars Technica has compiled a list of twelve features that they would like to see in iPhone OS 4.0. The final item on that list is multitasking and running multiple applications on the iPhone.
The reasons that Apple has given for not already including this feature on the first three iterations of the iPhone OS are perfectly valid. The battery life of the phone would suffer. There is limited memory. There are limited processor cycles. However, the iPhone seems to be directed towards technologically savvy consumers. One might reason that the majority of iPhone owners would be willing to suffer deteriorated battery life in order to get multitasking.
The usability issue with not having multitasking capabilities is that the user would have to leave an application in order to run another application. An example would be trying to send an email to schedule an appointment. One would have to leave Mail.app, open Calendar.app, get the desired information, and return to Mail.app to finish the email. This process may even have to be repeated several times in the course of writing that email.
Mac OS X has an excellent application switcher in the form of Cmd-Tab. There is no reason that some adaptation of this could not be ported to the iPhone. A shake gesture could be set up to call up the switcher. The double-press of the Home button could also be configured for this.
As for background applications, like an instant messenger application, those could be set up and enabled for background processes just like Apple has set up push notifications in iPhone OS 3.0. There is no need for an ugly Windows-style process manager. Just show a simple list of applications that have background capability and whether or not it is enabled. It could be as simple as that.
Apple has the ability to allow people who want multitasking and background processes to do it effectively. Hopefully, this feature will make an appearance in iPhone OS 4.0 sometime this year.