very miniscule spoiler:
I don't think Irina will be in this week's ep either, from what I've read she will be in Langley identifying voices in recordings in exchange for being able to see Syd graduate.
I agree with most of what was said above, that Irina was behind the plot but perhaps not the whole thing. Sark seems to have alot of leeway, she may have told him a specific task to get done, but left to his discretion how to do it. I think the whole Francie thing was Sloane and Sark's doing, probably without Irina's knowledge, since it would serve her any purpose, but to have someone watching Syd would serve Sloane's purpose alot.
Think of the situation like this, when 3 armies of equal manpower and firepower meet on a battlefield, it will be a stalemate 3 ways unless two forces join together against a third one. Then the final two can be left to duke it out. Between the CIA(and other good guys sponsored nationally), Alliance, K-Directorate and the Man, it was something of a stalemate with too many players on the feild.
If Rambaldi's prophecy is correct, and the man has never been wrong, Irina will render a great power into desolation, bring forth his works, and use them in anger and fury. Well, the Alliance is down for the count. This is after she and her errand boy Sark side with enemies, she with CIA and he with Alliance, to take down the common enemy. Now that the Alliance is down, I predict that Irina will either escape (for which I'm sure she's planned) or continue to aid the CIA in tracking other bad guys until only her own organization is left. Then she WILL escape and resume control, hopefully by then the Rambaldi puzzle will be solved.
Another minor spoiler:
Sloane will kidnap a scientist and order him to construct the Rambaldi device from the collected peices.
Sloane probably believes he is working with Sark, believing Irina is gone or hiding. I figure they are playing him the way he played the Bristows and the Alliance. He'll have the device finished about the time Irina shows up and the prophecy will be fulfilled.
What about Sydney? I tuly think Irina DOES love her daughter, because (Spoiler) in the same episode with the scientist, Syd comes to tell her she's thinking about quitting the CIA, which means she'll loose clearance to see Irina. Irina will then tell her to do it, quit and go have a life, and if Syd won't, then Irina won't talk to her anymore. It would seem Irina wants her kid out of the line of fire.
The "vulgar cost" mentioned in the prophecy might well be Sydney, Irina may have to choose what's more important to her, her daughter or global domination.
Just a theory of course.
---Ashley