Redmond Pie claims “Apple will demo iPhone OS 4.0 on March 14”.

We consider that unlikely as March 14 is a Sunday.

Claimed improvements:

• There will be multi-touch gestures OS-wide.
• “A few new ways” to run applications in the background — multitasking.
• Many graphical and UI changes
• The update will supposedly be available for only the iPhone 3G and 3GS, but will “put them ahead in the smartphone market because it will make them more like full-fledged computers” more than any other phone to date. Everyone is “really excited.”
• The last piece of information is the most vague, but apparently there will be some brand new syncing ability for the contacts and calendar applications.

Take a look at the Redmond Pie report.