For those of you who don't have the time to read all the spoilers, I've decided to collate the key non-episode specific ones. New spoilers will appear at the end of the list.
Spoiler 1 : Jacks Tattoo will be explained in a flashback
Spoiler 2 : We will learn more about Libby through flashbacks
Spoiler 3 : We will see more of Danielle in Season 3
Spoiler 4 : Desmond has join as a main cast member for Season 3
Spoiler 5 : There will be new locations inc underwater set shown in Season 3
Spoiler 6 : Michael Emerson (Fake Henry Gale) will be series regular
Spoiler 7 : Michael will only be a guest star in Season 3
Spoiler 8 : Chances to see Ana-Lucia in flashbacks are slim to none
Spoiler 9 : We will see more of Alex next season
Spoiler 10 : The island was visible for an instant on 9/22/04
Spoiler 11 : The foot statue represents the history and archeology of the island
Spoiler 12 : Kimberley Joseph is returning as Cindy in season 3
Spoiler 13 : Locke, Eko & Desmond are all back
Spoiler 14 : Fake Henry was not surprised by the failsafe activation
Spoiler 15 : DHARMA = Department of Heuristics and Research on Material Applications
Spoiler 16 : Juliet, a woman in her mid-30s, will be added to the cast as a regular
Spoiler 17 : This season we will learn a lot more about the Others
Spoiler 18 : There will be several new romances on the show this year
Spoiler 19 : Locke will be a very different person in Season 3
Spoiler 20 : Penny will be an important character for Season 3
Spoiler 21 : The Relationship between the outside world and the island will be explored
Spoiler 22 : The monster and the polar bear will be back in Season 3
Spoiler 23 : The smoke creature and the monster are one and the Same
Spoiler 24 : An event will happen mid-season that will blow people away
Spoiler 25 : We will learn why Locke was paralyzed
Spoiler 26 : We will learn why Libby was in the asylum
Spoiler 27 : We will learn why the island has healing powers.
Spoiler 28 : Time may not be passing on the island at the same rate as off the island.
Spoiler 29 : Rodrigo Santoro is the new male cast member who will play a survivor
Spoiler 30 : Elizabeth Mitchell is one of the new female cast members who plays Juliet
Spoiler 31 : Rose has a daughter
Spoiler 32 : We will understand more about the Whispers
Spoiler 33 : Goodwin will be back in flashbacks
Spoiler 34 : Kiele Sanchez will join the cast and play Rodrigos love interest
Spoiler 35 : Jin will speak more English in season 3
Spoiler 36 : Shannon will be back in a flashback
Spoiler 37 : Jacks's wife Sarah will be back in a flashback
Spoiler 38 : Julie Adams will appear as a recurring character
Spoiler 39 : Jack has met one of the Others in a flashback
Spoiler 40 : Kate possibly does not choose Saywer
Spoiler 41 : Ethan will be back
Spoiler 42 : The hatch is gone
Spoiler 43 : Rodrigo won't appear until February
Spoiler 44 : New character Colleen will be introduced in Episode 3
Spoiler 45 : New character Stucky Chavez will be introduced in Episode 4
Spoiler 46 : Boone has been seen filming.
Spoiler 2 : We will learn more about Libby through flashbacks
Spoiler 3 : We will see more of Danielle in Season 3
Spoiler 4 : Desmond has join as a main cast member for Season 3
Spoiler 5 : There will be new locations inc underwater set shown in Season 3
Spoiler 6 : Michael Emerson (Fake Henry Gale) will be series regular
Spoiler 7 : Michael will only be a guest star in Season 3
Spoiler 8 : Chances to see Ana-Lucia in flashbacks are slim to none
Spoiler 9 : We will see more of Alex next season
Spoiler 10 : The island was visible for an instant on 9/22/04
Spoiler 11 : The foot statue represents the history and archeology of the island
Spoiler 12 : Kimberley Joseph is returning as Cindy in season 3
Spoiler 13 : Locke, Eko & Desmond are all back
Spoiler 14 : Fake Henry was not surprised by the failsafe activation
Spoiler 15 : DHARMA = Department of Heuristics and Research on Material Applications
Spoiler 16 : Juliet, a woman in her mid-30s, will be added to the cast as a regular
Spoiler 17 : This season we will learn a lot more about the Others
Spoiler 18 : There will be several new romances on the show this year
Spoiler 19 : Locke will be a very different person in Season 3
Spoiler 20 : Penny will be an important character for Season 3
Spoiler 21 : The Relationship between the outside world and the island will be explored
Spoiler 22 : The monster and the polar bear will be back in Season 3
Spoiler 23 : The smoke creature and the monster are one and the Same
Spoiler 24 : An event will happen mid-season that will blow people away
Spoiler 25 : We will learn why Locke was paralyzed
Spoiler 26 : We will learn why Libby was in the asylum
Spoiler 27 : We will learn why the island has healing powers.
Spoiler 28 : Time may not be passing on the island at the same rate as off the island.
Spoiler 29 : Rodrigo Santoro is the new male cast member who will play a survivor
Spoiler 30 : Elizabeth Mitchell is one of the new female cast members who plays Juliet
Spoiler 31 : Rose has a daughter
Spoiler 32 : We will understand more about the Whispers
Spoiler 33 : Goodwin will be back in flashbacks
Spoiler 34 : Kiele Sanchez will join the cast and play Rodrigos love interest
Spoiler 35 : Jin will speak more English in season 3
Spoiler 36 : Shannon will be back in a flashback
Spoiler 37 : Jacks's wife Sarah will be back in a flashback
Spoiler 38 : Julie Adams will appear as a recurring character
Spoiler 39 : Jack has met one of the Others in a flashback
Spoiler 40 : Kate possibly does not choose Saywer
Spoiler 41 : Ethan will be back
Spoiler 42 : The hatch is gone
Spoiler 44 : New character Colleen will be introduced in Episode 3
Spoiler 45 : New character Stucky Chavez will be introduced in Episode 4
Spoiler 46 : Boone has been seen filming.
