I am not really of the mind that Bush is all about rounding up the world's oil supplies, but a lot of other people are, and you can read speculations about it here and here, and further conspiracy theory here.
The pipeline thing, by the way, is happening in several places. The Caspian Sea, Europe, and Siberia, where Japan and China are tusseling over who ends up at the receiving end of one.
Anyway, yes, I think oil is part of the equation of what we are doing, but no, I don't think it's the grand plan. I just think it happens to kill three birds with one stone. (Terror, Middle East peace, and access to oil on the free market.) And you know what, if we weren't doing it, you can bet that China would be out there in much fuller force than it already is.
Finally, when you're in charge of the largest economy in the world, which is also the world's largest oil consumer and the world's largest oil importer, the reality is that you're going to have to knock a few heads around.