I think it's important to remember that while metaphor vs. metonymy is an interesting debate for those who are interested, the key isn't so much what we call the figure of speech but rather what the author uses it to mean.
Even something as simple as the phrase "the White House announced" or "the Pentagon announced" is packed with meaning. Obviously, the building is not talking, a person is. What person? Who cares? Just a press secretary or other functionary. Their name is not important; they are speaking for a much larger organization.
And the person isn't speaking for "the White House" -- they're speaking for the president's administration, particularly the upper levels who actually work in the White House as opposed to next door. But we as a society picture these pronouncements coming from our stately government buildings. It seems to add a certain gravity and solidity when you picture a stone building instead of just a bunch of guys.