I'm guessing it's from Blizzcon, but I'm kinda leaning towards the announcement of the next WoW expansion this year. Seems to be the time for it.

@Kaphik

I think Diablo 3 is far more likely than news on WoW's next expansion... I mean, we haven't even gotten the second tier of content yet and the game has been out since December... it has almost been six months! Firelands will probably last at least another three months and then Blizz will probably do some raids themed around the Abyssal Maw/Vashj'ir. Once that tier is over, then we may or may not see Deathwing's tier of content. What ever the case, that is another 9 months or so. To cap it off, we know that Deathwing is closely related to the Old Gods and Chris Metzen has hinted that N'Zoth might have a part to play in Cataclysm.... so another potential raiding tier.

It is possible that they will bring up the next expansion but if they do, I am guessing that it will probably be only a very small teaser.

Out game events (blizzcon etc) or paid game events like arena pass:
-Murloc pet! murky, deathy, grunty, murloc costume, murkimus

Collectors edition (with exception of vanilla):
-Whelps! Frosty, Netherwhelp, lil' deathwing, Onyxia whelp


Its definitely Blizzcon pet, no question about it. Diablo III CE pet wouldnt be coming this fast to datafiles and it def wouldnt be murloc. It would be special like Thor is.
Diablo III will be in pretty big light this year, it seems.