One complaint commonly leveled against the iPhone is that it can't run multiple apps at the same time. However, sources for AppleInsider say that Apple is finally planning to incorporate a task manager that will integrate with the established iPhone user interface in the next major revision of iPhone OS, expected to be available this summer.

Like Mac OS X on which it is based, iPhone OS is fully capable of running multiple processes at once. In fact, it does run multiple processes—iPod, Mail, voicemail and phone processes continually run in the background. What it doesn't do is run multiple third-party apps at the same time. Want to listen to Pandora while answering e-mails? Run a GPS tracking app while checking your tweets? Sorry, no can do.

Apple has given a number of reasons for enforcing this limitation. The company claims that multiple apps running simultaneously will run down the battery faster, or could lead to more out-of-memory errors as apps contend for the constrained resources of the iPhone. Also, since non-Apple apps can't run in the background, there's virtually zero chance that malware could run without a user noticing. Finally, limiting the iPhone to one app at a time keeps things simple enough for even the most tech-averse users to understand how it works.

However, the latest rumor says that Apple has a "full-on solution" to the problem coming in iPhone OS 4.0. No specifics were revealed, so there are no details about how Apple has implemented managing multiple running apps. Remember, it took three major versions of iPhone OS before there was system-wide cut-copy-paste functionality, and the interface ended up working extremely well. We expect Apple has likewise put extensive work into making running multiple apps as straightforward as possible while still offering reasonable levels of stability, battery life, security, and ease of use.