SPOILERS AHEAD: Don’t read further unless you’ve seen the Lost episode “One of Us”.
Still there? OK. A couple of questions: How did Juliette know about the man Sawyer killed in Australia? How would Mikhail be able to get files on all passengers on flight 815, as Ben requested?
Well, the easy answer to this is that whatever large network The Others have on the mainland was utilized to get the information. That might work for the passengers on the plane, but how in the heck did they get that information about Sawyer?
There are two ways. First, it might be this mysterious “Jacob” they keep referring to. I don’t think that’s it. That’s putting way too much into someone (or something) we haven’t even seen yet.
The second, and much more plausible answer, is The Smoke Monster. It’s already scanned the minds of various people on the island. It might have even scanned most of the people on the island. If The Others are in able to communicate with The Smoke Monster that might just be how they got all the information so fast. Now, I’m using the term “communicate” very loosely here. They might just be able to eavesdrop on it’s abilities, or maybe read it’s “mind”. Mikhail had a lot of equipment in that complex of his. There may be a frequency he could tap into and “see” what The Smoke Monster sees.