Here's what I've managed to gather so far, as of episode 14:
Broad political stuff
--Some scientist guy out in the colonies was pissed off that the Alliance had oppressed them in the name of peace, so he created a bunch of Gundams and sent them off to Earth to attack OZ.
--The Alliance initially had the very noble goal of oppressing everybody to gain peace, but has since become corrupt and war-torn.
--OZ, led by Treize, is using a carefully engineered attack by the Gundams as an excuse to engage in a coup to take down the corrupt Alliance and replace it with the fresh new OZ in the name of
--The Romefeller Foundation, a retarded old organization led by retarded old European royalty, originally sponsored the Alliance and now sponsors OZ because they think constant warfare is, like, totally cool, man.
--There are also individual regimes within the Alliance that are squabbling and fighting.
Here's one thing I don't get: if it was initially the Alliance that oppressed the colonies, and OZ later emerged from within the Alliance to smack it down, why is the mad scientist professor guy targeting OZ in particular? If anything, wouldn't he want to go after the Romefeller Foundation itself for continually sponsoring this cycle of war that gets the colonies caught in the middle?
Individual character stuff (in rough order of how interested I am)
--Treize is well aware that he is not a good guy bringing happy fun peace to the world, as he likes to convince his supporters that he is, but believes what he is doing is nonetheless necessary.
--Relena is now being introduced to the basic political situation by Noin, but still can't seem to grasp that it's more complicated than "bad people make war now kill daddy." Not that I blame her, as from the point of view of a teenager who's just lost her beloved father, it's probably hard to appreciate the complexities. I'm just glad she hasn't suddenly totally matured already and become completely wise in the ways of the world, as I was afraid she would for a bit; that would be ridiculous.
--Zechs fights primarily because he wants to restore the Sanc Kingdom, but has become mired in his own hatred, need for vengeance, and addiction to war. (Haha, I slipped and used a term I liked to use about Mwu, didn't I? Where the hell is your range, Koyasu?) I can't tell yet why he's willing to fight under Treize, though, or exactly how much he knows.
--Noin knows more about Zechs than pretty much anyone else and seems to be acting as his aide in achieving his political goals at the moment. Does she know as much as him? Less? More? What about her own goals, of setting aside her weakness and fear and becoming strong enough to fight?
--The five Gundam boys don't really seem to know much about the underlying politics, just that they want to fight to help out their colonies and they've been told that OZ is the bad guy.
I admit, Zechs, Noin, and their goals are what confuse me the most. I hope that's what's supposed to be confusing me, though.