Ok here's the significant details on the remainder of the book:
The Elemental Chaos:
An evolution of the inner planes better suited to adventuring (and not just one homogenous mass of element) - more dangerous than lethal.
Inahbitants include: Primordials, Elementals, Efreet, Djinn, Demons, Slaads, Titans, Githzerai
The City of Brass is mentioned as a location of note
The concept of "Elemental Evil" as represented in TOEE is recognized as core, on par with the Nine Hells
Consists of four factions with noteworthy differences between them. A 'fire elemental' can refer to any of a number of different shaped creatures, which can be composed of more than just fire; a 'serpentine trail of flame that spits magma' or a 'hill-giant sized humanoid of burning cinders who breathes gouts of fire' are given as examples
The Abyss is now part of the Elemental Chaos, with the stock Demon Princes recast as corrupted primordials
'at least one Demon Lord' appears in the Monster manual as an epic level adversary
They were considering at time of press allowing demons to gain immunity to a damage type of their choosing a few times per day
Mezzoloths and Nycaloths are now Mezzodemons and Nycademons (of which the first is confirmed to be in the Monster Manual)
The Astral Sea:
Counterpart to the Elemental Chaos
Inahbitants include: Gods, Angels, Devils,
Dominions, especially Abandoned ones, found throughout the Astral Sea are 'adventure sites custom made for epic characters'
Continuing the theme, the Astral Sea and its Dominions are much easier to play in, at least for epic level characters.
The pantheon mentioned is: Bahamut, Vecna, Avandra, Zehir, Ioun, Pelor, Tiamat, Gruumsh, Lolth, Corellon, Moradin, Kord, Bane, The Raven Queen, Asmodeus, Torog
The full pantheon has 'twenty plus one' gods
The gods are less connected with Race
There are Angels for all gods, both good and bad- they are described as 'the cold, clinical expression of a deity's plans' and 'the frontline warriors in the wars amongst the gods'. Some interesting fluff to back all that up.
Demons and Devils are more distinct in battle. This is summarized as:
- 'Demons are chaotic, Devils are organized'
- 'Demons kill, Devils subvert'
- 'Demons are tough, Devils are slippery'
The section 'Staff thoughts on 4th Edition' is largely reprinted material from blogs and articles
Lastly thought I'd point out that they explicitly state that the bronze and brass dragons will be released by WOTC in a future supplement.