iPhone OS 4.0 Detailed: Multitasking & New UI But iPhone 3G/3GS Only?

Apple's press event next Wednesday – which SlashGear will be liveblogging – isn't just expected to see their tablet debut, but the latest version of iPhone OS too, v4.0.  Last we heard, Apple had been sitting on a significant update for the iPhone and iPod touch because there were too many tablet-tipping tidbits in there; now, BGR have supposedly heard about some of the more appealing feature-adds, including the introduction of "a few new ways" to run apps in the background.

Also tipped are various UI and graphical changes, that have apparently been made to improve and streamline navigation, together with OS-wide support for multitouch gestures.  Meanwhile there's some vague talk of new synchronization options for the calendar and contacts, though no exact details of what that might be.

Unfortunately for first-gen iPhone owners, however, it seems they'll be left out of the upgrade to iPhone OS 4.0.  Only iPhone 3G and 3GS handsets will apparently get the software, which will "put them ahead in the smartphone market because it will make them more like full-fledged computers."  The unnamed source goes on to say that everyone involved at Apple is "really excited", though we imagine that's a mandatory state of affairs in Cupertino; he also suggests that the Apple tablet will not be called the iSlate, as previously tipped, but the iTablet.