When Desmond slammed Mikhail up against the tree I was expecting to hear a similiar speach like he gave to Sayid.
"Of Course I don't know you...Desmond Hume..."
In actuality Mikhail didn't really seem to show any recognition towards Desmond at all.
Desmond's still an x-factor to the others, maybe.

Presumably the Others know of him if they've been monitoring the Swan Station - he was there for three years. Then again, they may not know his name - the implication was that Mikhail was able to obtain a passenger/crew list for the doomed flight, Ethan and Goodwin lists of the survivors, and their PIs on the outside world did the rest. Unless Kelvin was an Other - I don't think so - the most they might have known about Desmond was his first name (and maybe not even that, if their surveillance equipment doesn't have sound).

Juliet didn't seem to know as much about Sun as she did about Jack either...she'd know about it if Jack had had an affair in the last couple of years. I reckon the Others only do all these massive background checks on the people who are on this infamous 'list' that they're keeping all hush-hush. They just know a couple of things about the lesser characters.

"Of Course I don't know you...Desmond Hume..."
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hahaah!that cracked me up!hahah!everythings become so predictable ,huh!we read so much into anything ,we could become the next eddie kitsis!:)