Sorry, several Warseer veterans found it funny to post made up false rumours in March and call it April fools. Shame on them.
So all the new stuff in this summary is no rumour at all. The thread can now be closed
Seems like the rumours on the upcoming Dark Eldar release get a bit more concrete. I will take the new Warseer thread as a basis:
http://www.warseer.com/forums/showthread.php?t=251993 and try to keep this first post updated with information from that thread and this one. As this is again much work, I will leave out explicit credits to the posters of each information in these threads (mostly found in first post of Warseer thread) but like to express my sincere thanks to all of them.
Of course keep in mind that these are just rumours, some of them with (to me) unknown sources. Still this summary should get closer to the mark given time.
General
The Codex is ready, translated but not at the printers yet (24th March). Not known if it will get the Oct.2010 or January 2011 slot for its release (pending marketing decision after Easter). Others put the release later, most within 12 months.
Background may be (re)written but keeps the general theme.
One podcast is certain that
DE are the next Codex and due this year. Others are certain that Grey Knights will be next and due this year.
Rumours of an official announcement pretty soon.
Background
As Craftworld Eldar technology is based on Wraithbone, all
DE technology is based on pain as a power source. All major vehicles are powered by flayed slaves, and jetbikes, skyboards etc are said to be charged up before battle. All their ranged weapons have blades as a means of recharging them, even if it means cutting yourself.
This theme follows on into other equipment too, like the new power field for
ICs that is a 4+
Inv save that gets +1 to the roll for each wound the character has lost. It specifically tells you to roll each save separately so you can apply the appropriate bonus.
The
DE conquer and enslave an Imperial world, abandoning it only after the arrival of the Imperial Pacificus fleet.
A populated exodite world 'turns to darkness' after being infiltrated by a
DE Slaanesh cult, and after slaughtering wholesale those who oppose them, escape into the webway.
Units
Characters can get "Catcher of Souls", a power weapon (?) with a vampiric effect: wearer gets one life for each unsaved hit.
Another source says no power weapons in the Codex (Except
MC Talos) but lots of rending (and source="Thud" from Warseer is pretty sure about it).
Lots of new special characters and a new
HQ choice.
Several Psi powers (no general psi hate any more as it seems, but perils of the warp harder than for other races): "Dark Kiss" (?, target in 12" makes
ld test with 2 highest of
3d6, failure means target removed no questions asked and no saves allowed), "pain something" (target unit gets
FNP until their next round) plus 2 other less strong ones.
Special character "Asdrubael Vect"
Gets "terror field" (all enemy units retreat on 4+ no questions asked no special rules allowed)
Those 2 Incubi on the barge are "Black Guard" (they get 5 attacks while embarked, enemy can only hit barge not Incubi; every enemy killed in
cc will fuel the barge for +1" !)
Special Character "Enuviel the Dethroned"
Slaanesh worshipper. Cabal Lord (Dracon/Archon) of the old Ways. Makes the whole army Slaanesh worshippers (sigh!).
Special Character "Shlit'Endapo Nih"
(name only heard, not seen written). A wych with many attacks.
Haemunculi
A Haemunculi upgrade allows the
DE player to take control of a run down unit rather than destroying it.
Wyches
Different types of Wych weapons, not the current standardized ones. Rending in
cc. Can no longer get ranged weapon upgrades (Blasters etc).
Combat Drug rolls for wych cult amended to:
1. +1 S, Rage
2. I 10, ignores cover penalties
3. Furious Charge
4. Feel No Pain
5. 12" assault,
3d6" fall back
6. Choose one of the above.
Incubi
Rending
cc weapons and short ranged low
ap guns. Squad leader has "super-rending" weapon (think Skulltaker). Squad leader can get "Exarch power" resembling upgrades.
Warp Beasts
Unit Upgrade for a Wych Squad on foot/Equipment upgrade for a Succubus. Can be taken by any number of Succubi.
Talos
The Talos will be a walker "of sorts", with special rules increasing its durability. It will have a variety of options, including a "weaponised psyker" (psyker upgrade). They are Heavy, but can also be Elites if you take a Haemunculus as your
HQ.
Reavers
Reavers will be able to drag models away from units and drop them as a blast weapon.
Vehicle Upgrade "Shadow Field" (enemy must use Night Fight rules to target vehicle).
Dark Crow
Even more salt for this rumour entry: Fast attack choice (a Valkyrie equivalent?).
Weapons: 2 Dark Lances, Dark Shard Projector ( S5 AP4 Heavy 20, Pinning)
Special Rules: Deep Strike, Scout, Assault Vehicle, Dark Avarice? (don't know what that does)
Transport Capacity: May transport up to eight models.
Appearance described as "Jabba's Skiff" style transport.
Miniatures
Model range completely redone by Jes Goodwin. He got all the time he needed to get this done, therefore no estimated release date for several years. With that many new models, a release in waves sounds likely, with plastic warriors, wyches and Raiders/Ravagers likely candidates for a first wave (my conclusion, not exactly a rumour).
Warriors are like the one in the rulebook (
http://www.pbase.com/brimstone/image/97930904.jpg ), but spikier (10 per box for the usual price). Splinter rifle as seen in an early
CAD pic but spikier as well.
Plastic Wyches are basically just a direct copy of the current ones but in plastic (others deny that because sculptor Fitzpatrick has left
GW and the models are not popular), there will be a lot of 'fluff' pieces on the sprue (armour plates, trophies, that sort of thing) to make them more customisable. Also rumoured to come with a lot of weapon options, supposedly each weapon option is available for the entire squad. Again 10 per box.
New Incubi models look like a fusion of several
CWE Aspect Warriors. Poses are very dynamic like the 3rd edition Scorpions. Tormentor Helms now have masks similar to Jain Zarr, moulded to look like they are twisted in tortured agony and the ranged weapon is mounted on the left temple. Much heavier armoured like Dark Reapers, but covered with spikes and blades. Punishers are no longer 2 handed polearms, but are a pair of spiked cudgels with Splinter Pistols in the hilts. Drazhar won't be getting a new mini in the first wave, and will be discontinued until a new model can be made that fits the new asthetic.
Raider possibly as in the rulebook (
http://www.pbase.com/brimstone/image/97930903/large.jpg ) with sails.
Talos is getting a plastic model with loads of options.
" But I won't add that to the summary 
