"Ben begrudgingly begins to introduce Locke to the secrets of the
island, beginning with the mysterious Jacob."
TV-14
Tv.com has a more satisfying description:
"Ben unwillingly divulges information to Locke about the island,
taking him on a journey to various locations including strange
monuments and the mysterious Jacob. Back at the beach, Juliet's secret
is revealed. Flashbacks will show us the origins of DHARMA and the
history of the island, including 'the purge'."
I love the allusion in the title of this episode, likely referring
plot-wise to Jacob. This isn't the first time "Lost" has given a nod
to "The Wizard of Oz". If you recall, Ben called himself Henry Gale, a
name he stole from a dead parachutist in the show, and a name the
writers borrowed from the movie.
Also, the episode will be Ben-centric and Mikhail is supposed to have
an appearance.