So they updated the page at midnight, 2 hours and 45 minutes before the event.
The new picture is entitled ice5andhalf, which is the same picture on the main page.
The runes now all appear to be glowing glyphs, supporting the theory they are all activated and ready to release Diablo similar to that of act4.
The face has by far more detail, and it is quite clear this is not Arthas. I would say there are too many lines and angry details to support it being anything Starcraft (Tassadar has a much smoother visage), therefore it's gotta be big red.
There also appears to be a hand in the bottom right corner.
And finally, there is a winking smiley face on the top of the ice which really angers me. I want to shoot that thing in his happy little face and watch him bleed! Cruelty!
Edit: Friend of mine also just pointed out that there appears to be a red tint around the shattered ice, there appears to be a demon-slit nose forming, and if you notice his forehead is still in shadows at this point. Soulstone 101
The 6th splash image is online. ice5andahalf.jpg by name. The runes are now glowing, a rune has been added to let us know it's all a happy fun joke, and the face in the middle is clearer and more menacing, with glowing, smoking eyes and a bony brow ridge.
The new winking rune:
A closeup of the "face".
Can anyone make out the shape to the lower/right of the face? Looks like a narrow triangle; a church steeple, an old wizard in robes... can't tell. Magnified it's just pixelly and indecipherable.
On the whole thing, I think it's a clear Diablo reference. The face could be Diablo or any other skull-like bony demon type, or even a Protoss, but look at the runes? It's the Chaos Sanctuary! 5 seals that must be activated, and when they glow Diablo appears in the middle. there's even a winky face to let us in on the joke.
As for the runes, they were over analyzed. The first 3 were references to the 3 blizzard gameworlds, the 4th showed them all orbiting at once (3 new games, one in each world at WWI), and the 5th represents Blizzard itself. And now they're activating, which makes Diablo appear. Boom!
Also, as was pointed out in the news thread; where else in Diablo do we see 5 objects around a central glowing point?
OMG im soooooo happy right now i got the live feed on right now waiting for it to start playing already! we should all get some kind of instant chat thing going on before it starts. maybe the mods will throw us one? like a shout box maybe? idk but theres no way its not diablo AHHH EEEEE WOOO diablo 3 here we come!