The Link to AnandTech has a decent technical summary of the new models. I was planning on 8GB RAM and the 256GB SSD, but the annoying thing is that SSD is apparently priced off the charts compared to the 128GB, which is pretty much at market price. Still, I have to think that 128GB would feel limiting and I will definitely get AppleCare so replacing on my own is not an option.
And Dinny, the 27" iMac is amazing. Not portable, but a great desktop/TV/etc.