Was just reading the "Which guild will down Arthas HM" thread and more people then I expected seems to believe that Arthas HM will be killed by Premonition.
Basically, there is one very, very basic reason why this won't happen: Premonition have not killed Arthas on normal mode yet
I'm not doing this topic to bash Premonition, just want to educate the masses.
Do not worry though, Premonition recruited a player from a guild that has killed Arthas, so they are still, technically speaking, in the race.
[EDIT]
http://www.wowprogress.com/guild/us/sen-jin/Premonition
They recruited empyrea, a mage from juggernaut, who accomplished lk 25 with his guild yesterday.