Good episode. I like the fact that they have pretty much tied up the story up until this point. The end of season 3 gave us a forshadowing teaser and season 4 was used in filling in the blanks up to that point, with the end of the season going just a little beyond the point season 3 showed us.
My predictions: Season 5 will be all about how they get back to the island, with flash forwards to being on the island, and season 6 (the last) will be all about winning the island, and what it's all about.
Lost - best show ever.