Back story:
A terrible threat has been uncovered on the ice world of
Belsavis; a danger so grave that it could make the conflict between the
Republic and the Empire irrelevant. Groups of heroes must band together
to venture into the ancient and deadly Eternity Vault—where an enemy
older than both the Republic and the Empire has been contained... until
now.


Looking from the trailer, it seems that PvP is involved in the raid,
where the republic side has to defend the base while the sith side tries
to capture it.

BioWare and EA have released several videos at E3 2011, including cinematic trailer and gameplay video.