After the “Tablet” itself, one of the most anticipated announcements at today’s Apple Event is that of a new operating system — often called iPhone OS 4.0 by rumormongers, but we’ve heard other names for it — that would power the Tablet and be accompanied by a simpler variant for hand-held iDevices offering parallel new features. Here’s a summary of what we hope to see from Apple’s new system software.

These predictions are based on a combination of public information and reporting from our sources privy to iPhone OS development; they are based on projects we know are in the works for release by this summer at the Worldwide Developer Conference, and can only offer our best guesses until after today’s Event is over as to exactly when they will see public release.

New multi-touch input methods that Apple has been working on are primarily targeted at the Tablet and Macs under the “Magic Touch” banner, but there should be some new gestures that will fit into the 3.5-inch space provided by hand-held iDevices. There has been a lot of talk about “Newton-like” pen-style writing based text entry for the Tablet, but size limitations alone make it questionable how well that will carry over to hand-helds.

Voice Control will be improved and expanded to new areas of the system. Whether the advanced speech recognition for text entry that is possible on the powerful Tablet hardware will fully carry over to hand-helds has been a long-standing question that we haven’t received satisfactory answers to. Also, expect to see more voice recognition driven capabilities for application developers to utilize.

Multi-tasking, or at least a form of limited “backgrounding” one or more applications, has been a major goal of the Tablet software project. Again, such functionality has always been intended to be made available across the entire iDevice lineup right back to the original 2007 iPhone but the battery life penalty increases as one goes back through the 3GS/2009 iPod Touch hardware to the original 412MHz ARM11.

This should be the most interesting area of new functionality that we’ll be hearing about today.

There’s much more we’d like to get into, but it’s approaching time to begin our Live Coverage at http://macosrumors.com/2010/01/27/tablet-event-live/ so stay tuned for that and our post-Event analysis as well as our coverage of the lead-up to Macworld Expo San Francisco which begins this afternoon!