Although we've been running iPhone OS 4 -- now known as iOS 4 -- since it was first announced in April, we actually haven't been able to try out any of the fancy new multitasking features, since no third party apps have been released with support yet. That's all about to change: as of today, Apple is accepting iOS 4 apps, which means we should see quite a few apps that take advantage of multitasking on the iPhone 3GS and iPhone 4, as well as make use of
