Besides patents, what on earth is telling you there *might* be a new iMac touch screen in early 2011?
Firstly, Apple does not believe a touch screen interface is compatible with OS X. Watch the recent All Things Digital interview and listen to Job's thoughts on iOS.
And secondly, this Wednesday will mostly likely just reveal 10.7 Lion. Launch date will most likely be sometime in 2011, then factor in the shelf life of Lion before we even start talking about OSXI and any remote possibility of touch screen interactivity on Macs.
Touch screen Macs? Not in YEARS.