I'm excited about truer multitasking but thought after that feature was demoed a new Safari would be announced that supported the ability to display side by side pages. It seems a bit odd that you can do this now using two different browsers but still can't do it with only Safari. Is there a technical reason for this?
It's probably cause of the way it was designed to work. To obtain that you would have to have two safaris open (or two different browsers like you said). I wouldn't be surprised to see the feature you mentioned in future releases.
rather than then them fiddle around with allowing safari to run twice within the split screen framework and all the complications that could come from that, they could just add a way to display two tabs at once within one safari. wouldn't be surprised if this was a 9.x feature.