From what we know now about Season 5:
1) Time travel: The remaining survivors have been traveling between the past and the present.
- 1988: The most recent time period. Jin is in contact with Rousseau and her group.
- October 2004: Locke saw the light from the Hatch. Sawyer sees Aaron's birth.
- 1940s/1950s: Widmore and Hawking on the Island, with the original (?) Others, led by Richard.
- Between September and October (?) 2004: Faraday knocks on the door of the Hatch and talks with Desmond.
- December 2004: Locke meets up w/ Richard before going back in time.
I'm probably missing some, so please let me know if I am.
- 1970s: Faraday is seen under what (in the present, Island-time) is known as the Orchid.
- 2008 (?): Ajira Airways flight 316 from LA to Guam lands safely on the Island. Ben didn't time travel.
2) Piecing the plot together: The Oceanic 6
- Kate: Lived with Jack and raised Aaron for a period of around 2 years (a guesstimate). Split with Jack. On the run because of the investigation by Norton and Agostini. Back in Dharma-time with Jack and Hurley.
- Sayid: Broke Hurley out of Santa Rosa (I think that that's the name of the institution.) Attacked at the safe house. Brought to Jack by Hurley's dad. Recovered and attacked the hitman at the hospital. Left Ben, Jack, and Sun before appearing on the plane, handcuffed and shaved, with a federal agent (or so we think).
- Jack: Lived with Kate and raised Aaron for a period of around 2 years (a guesstimate). Resumed work at an LA hospital. Rediscovered the magic of pills and alcohol. Became a loner. L-O-N-E, loner. Lo-lo-lo-lo-loner. *insert parody of "Lola".* Grew a beard. At some point, he met with Locke/Bentham, who convinced Jack that they all had to go back. Met up with Ben at the funeral home and began the process of getting everyone back together to return to the Island. Back in Dharma-time on the Island.
- Sun: Presumed to be working with Widmore to get to/back to the Island. No clue if she's back in Dharma-time or the present with the Ajira Airways survivors.
- Hurley: Still didn't lose any weight. Sees dead people from the Island (Charlie, Ana Lucia). In lock-up after turning himself over to the cops to get away from Ben. Out and back on the Island in Dharma-time.
3) Other people: On/off the Island
- Locke: Presumed to have turned the Donkey Wheel on the Island, leaving the Island and making it to the present, talking with some of the Oceanic 6 before dying.
- Eloise/Ellie Hawking: Most definitely the mother of Faraday. Left the Island, presumably around the same time as Widmore for reasons still unknown.
- Charles Widmore: On the Island in the 1940s/1950s. Left by turning the Frozen Donkey Wheel (FDW) under Ben's orders.
- Rousseau: Finally! Now, we'll get some backstory on her time on the Island before Oceanic flight 815 crashed!
- Charlotte: My guess is that Charlotte was born on the Island, however, we don't know much about that. But, there will be a birth on the Island in the next episode, during Dharma-time. Things seem to be falling into place.
- Miles: Since his nosebleed was delayed, it can be inferred that he was on the Island for some extended point of time in the past. How many Asian babies have there been on the Island? One. *insert "One".* And that baby was the son of Pierre Chang/Marvin Candle/Edward Halliwax/Marvin (?) Wickman. So ... Miles is the son of the man formerly known as Candle (TMFKAC) and he (Miles) probably got off the Island sometime around the Purge. However, I don't know when exactly. Remember the video shown at Comic Con with TMFKAC? There was a baby crying the background and it sounded like Faraday was giving orders/instructions to TMFKAC. I'm thinking that, somehow, the survivors left on the Island get baby Miles off the Island and get someone to raise him.
- Baby Charlie (Des and Penny's kid): He will most likely pop up in LA with Des and Penny. Des will most likely have to go back, and perhaps with Penny and Charlie and the Oceanic 6 and Locke. There have been theories floating around online that the people returning to the Island will arrive there during the 1930s (Island-time). Charlie will grow up, take the maiden name of his mother, Penny, as his own last name. Hence, Des and Penny's son becomes Penny's father. Holy mindf***, Batman!
- The other survivors of the Oceanic plane crash: In the present (I think).
And I think that that's it. Am I missing anything? Feel free to let me know in the comments and I'll update it. And I'll probably update it weekly. Now, if you'll excuse me, I need some sleep.