I hadn't planned on doing a full recap and I missed a lot, believe it or not, so I'll link you to EW Lost Recap by Doc Jensen since he is always excellent and to Television without Pity's recap (when they are up) if you want more or a better picture of what happeneded. Here is Watch with Kirsten's Lost Redux as well.
So here is a brief summary of the 1977 plotline.
1977 Dharma - Jack, Sayid, Richard, and Ellie get the core of the bomb out and put it in a knapsack and then Richard knocks Ellie out and says it is his job to protect the leader and she is pregnant anyway so he drags her away and it's up to Jack and Sayid now. Radzinsky is still an asshole and not a listener so he drills into the pocket of electromagnetic energy. Jack and Sawyer have a big knock down drag out fight and it is not cool but Juliet stops Sawyer. Earlier, we ran into Rose! and Bernard! with Vincent! and they were all living a good peaceful life and Rose wanted nothing to do with the Runaround Gang. She says (and I think it might be significant) that they are always finding new ways to shoot each other and they (Rose and Bernard) are happy with each other for the time that they have. Juliet looks at Sawyer who looks at Kate and then Juliet looks sad. So, anyway, big fight, but it's decided to let Jack try. So off he runs (since Sayid got shot earlier) and then shootout shootout drops bomb into hole and then nothing. And then the electronmagetic energy kicks in and sucks everything metal down the hole, but sadly not Radzinsky who tries to DRIVE AWAY in a METAL jeep but has to settle for running. But heartbreakingly Juliet gets a chain wrapped around her waist and is pulled down and Sawyer and Kate try to save her but they can't and there is crying by everyone and she lets go and down she goes. I cried. And then Juliet wakes up and spots the bomb and bangs on it with a rock and big white light LOST. But a whole lot more happened so on I go.
Continue to here for the Jacob/Locke plotline and here for my thoughts and theories.