But I am sure everyone is dying to know: where did these gods come from...instead of staring another thread, lets try it here:
Asmodeus: Gary Gygax based on ?
Avandra: 4E creation?
Bahamut: Gary Gygax based on ?
Bane: Ed Greenwood (?)
Corellon: Jim Ward in the orginal Deities and Demigods
Erathis: 4E creation?
Gruumsh: Jim Ward in the orginal Deities and Demigods
Ioun: 4E creation?
Kord: Gary Gygax
Lolth: Gary Gygax
Melora: Pre 4E I think
Moradin: Jim Ward in the orginal Deities and Demigods
Pelor: Gary Gygax
Sehanine: Pre 4E I think
Tharizdun: Robert Kuntz (ya, thats right)
The Raven Queen: 4E creation
Tiamat: Gary Gygax based on Babylonian Mythology (?)
Torog: 4E creation
Vecna: Brian Blume (ya, thats right, though as artifacts, not a god).
Zehir: 4E creation?
I guess Heironeous isn't on the list because he didn't die, he just got ret-conned.
"Orcus wields an artifact called the Wand of Orcus. Legends say that the skull atop the wand once belonged to a god of virtue and chivalry who dared challenge Orcus in battle."
I'm pretty sure this was Amoth. Orcus, Rimmon, and Demogorgon assaulted Amoth. Rimmon was slain, Demogorgon was split nearly in twain, and Orcus struck the fatal blow.
Also bane while similar to the Bane of FR, is also very different from that Bane. I think they just re-appropriated the name. At least I recall something like that being said by a dev when 4E was just being teased.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.