Some 'unofficial' news, NOT confirmed but carries some info apparently gleaned from Alpha testing.
Summarised below thanks to someone on Reddit:
Dark Zones are entered seamlessly, but you must go through a "decontamination chamber" to enter them
Player count in Dark Zones will be 50-100 players
You receive a meter akin to a Wanted Level which makes you more visible/notorious and easier for players to find you
You have the option to find and work with other teams you come across in the dark zones
There are dynamic missions (possibly public events) and NPCs in the dark zones
Loot found will be "contaminated" and must be decontaminated before you can use it
Go bag will be split into 2 sections, Normal Items and Rare/Contaminated Items with higher stats
There are colors/shaders you can apply to weapons
Social Zones will likely contain over 100 players
Alpha testers have noticed game world changing in real time (lighting, walled off areas, closed buildings on the fly by the dev team)
Destruction is a big part of the game
Skill trees can let you see through walls and with the right weapon and ammo you can shoot enemies through the walls
Group AI will be similar to Assassins Creed with a Group Leader that gives a moral/stat buff to surrounding enemies
Enemies will be extremely aggressive
One scenario described a heavily armored enemy throwing a flashbang and then instructing other enemies to flank the players
Enemies have sniper rifles, flash bangs, shields, and flamethrowers
Weapon system similar to Ghost Recon: Future Soldier
Map size could be as large, if not larger than GTAV
Alpha Tester area is approximately the size of Downtown Los Santos in GTAV, the rest is walled off
Crafting includes scopes, barrels, suppressors, magazines etc
Each item quality is graded by Green/Blue/Purple etc
Armor and gear (hat, gloves) can be crafted as well
The color of clothing seems realistic (i.e. no hot pink agents roaming NYC)
Your crafted item is unique to you
Gear will be visibly rare to others
Controls are receiving very positive feedback
Controls akin to Ghost Recon and Splinter Cell Blacklist
Online is working well - one tester got kicked out but the game automatically rejoined him
Alpha testers saying there's "no reason to worry" it's already running great, better than some fully released games today and shouldn't have any issue releasing on holiday 2015