It appears that John Swenson was/is one of the beta testers of the Touch.
Here is a link to some of his comments.
The main points I get out of it is that the touch is using a 500 MHz ARM processor with linux.
John thinks the analog output is a bit better then the SB3. It is using an AKM-AK4420 DAC with a 2 volt buffered output.
He feels the digital output, which can natively pass 24/96, is better then the SB3.
He has also hacked the Touch to run a USB DAC from the USB connection on the Touch. He may offer this hack as an app.
It looks like the Touch will offer lots of fun for interesting apps and mods when it is released.