Just found this over at firing squad, its a more detailed post (no testing) on what the 5970 EF mode will be able to do on release.. Not as extensive as you would think - but atleast it does prove they are working on it.
Sorry if its in the links above somewhere, but got most the info I needed out of previews I had seen already :P
As an added bonus for Radeon 5970 users however, ATI is providing very limited Eyefinity support to the 5970 only. The 8.663.1 driver contains beta Eyefinity support for over a dozen different titles:
Anno 1404 (aka Dawn of Discovery)
Batman: Arkham Asylum
BattleForge
Call of Duty 4 – Modern Warfare
Call of Duty 5 – World at War
Call of Juarez: Bound in Blood
Crysis
Crysis Warhead
Dawn of War 2 (Warhammer 40K)
Elder Scrolls IV: Oblivion
Enemy Territory – Quake Wars
Fallout 3
Far Cry 2
GhostBusters
Left 4 Dead
Need for Speed: Shift
RaceDriver: GRID
STALKER Clear Sky
Tom Clancy’s HAWX
Unreal Tournament 3
World of Warcraft (plus expansions)
Now the Eyefinity support does come with a number of caveats. For starters, support is limited to the games listed above only. No other games are supported yet at this time. In addition, only landscape configurations scale properly. Running portrait mode will still function, but will rely on the primary GPU only. And again, Eyefinity support is limited to the 5970 card at this time.