Miles is probably right in recommending the other "space battle" thread, but if you're talking about near-term space warfare it is, at present, almost exclusively occupied with the use of satellites and anti-satellite weapons. Present "spacelift" technology isn't up to putting the sort of masses into orbit which would be required for serious weaponization. The ASAT programs are rather well documented online and in print, so I recommend a little Googling.

I think it would be neat to speculate about space war in say the next fifty years. Consider how crucial satellites  are to the American military. It seems an obvious link to attack. Say the Chinese, or Russians, or say the EU turns hostile and they start threatening or satilite nets. What steps would we take to protect them? Hardened satellites, satellites with onboard weapon systems? Would we develope mass launching techniques to lreplace vital satellites in a high lossy orbital environment? In the First World War there appeared the airplane, first as a scout. Then the pursuit planes came along to knock out the scouts, then bombers...just the other day I read an article in Popular Mechanics that the Marines are thinking about orbital insertion on a craft that reminds me of Scaled Composite's Spaceship One. 

I've heard of these kinds of kinetic kill weapons discussed as orbital bombardment systems. The concept has been around a long time. The "Rods of God" are an elaboration of this theme. I think this is something we will see in the near future. I've heard of smaller systems that would saturate an area with hypersonic pellets. The effect would be devastating. I can see why this might alienate some of our more difficult allies. Nuke tipped missiles are a dirty option, and space borne KKWs remove the radiation component. This kind of goes against the MAD policy operative throughout the Cold War. Without that nasty radiation lingering around, it's possible some politicans might find war more attractive than before. 

Several folks- including people on this board- have commented on the Rods of God concept. Those with an engineering background tend (characteristically) to be against it on several grounds: Engineering, economics, and politics.
The most common argument is that it's a gross waste of resources; a good rundown of why is here, but he does point out that the scheme Heinlein used in The Moon is a Harsh Mistress is quite workable. Simply put, the amount of bang for your buck is minimal compared with nuclear weapons.
But...
War is ever a political beast. You can't divorce war from politics. And the political implications of nuclear first-use are unacceptable for most Western or Westernized nations. So the idea has some advantages. I still think that the economic problems would rule the system out on practical grounds, at least until we have that major spacelift breakthrough I keep harping on.
But...
The current proposal to deploy conventional-armed ICBMs almost renders the question moot. If they're willing to shell out ICBM money to put a ton of HE on a target of opportunity, they might be willing to spend the exorbitant amounts required to put guided osmium telephone poles in orbit.
This leaves a final barrier: weaponizing space is still taboo. The stationing of WMD in space is prohibited by the Outer Space Treaty of 1967. Are the Rods actually WMD? You can argue that 'til sunup. The potential recipients will be the loudest criers, but Europe/Russia/China will be lining up against it too. (The Sino-Soviets, I mean, Russians and Chinese will only whine until they have a comparable system in place.)
So in closing, it makes for interesting speculation, but it's impractical on a number of grounds.

Good points. My understanding follows:
1.) Manuever. You can keep a satellite alive for a few extra passes by changing its orbit. Eventually you're run out of reaction mass, but that may buy you time to deploy...
2.) "Hot" spares. Papers on this subject refer to spare satellites being parked in orbit for contingency use. This may not be the case at present, but the possibility remains open.
3.) "Cold" spares. It might be more economical to keep a few spare comsats at Vandenberg and Patrick, and orbit them on an as-needed basis. If the US is faced with another cold war, I see this as the most likely option.

As for Marines in spaaaaaaaace, hereafter referred to as cap troopers, real-life proposals goe at least as far back as 1966 when this proposal came out, followed later by this slightly different proposal to station two Marine-carrying rockets on an Enterprise-class CVN.
 For all its potential faults, cap troopers have an appeal all their own. My biggest question is how the hell you're going to keep them supplied and provide fire support. We don't have ortillery yet, for reasons mentioned previously!

I think the Outer Space Treaty is explained by its context; 1967 was, after all, the middle of the Cold War and both power were keen to avoid an arms race in space. Inasmuch as it seems to have worked, we were (and are) better off for it.