In essence, is Portal trying to bring to mind the delusional world we live in, or bringing to our attention that the "cake" is a journey? (One take)
Another take on Portal's narrative: a warning of technological control.
All things are made by people, so why does Glados control? A likely conclusion might be he was made by the government to control, but he became too unstable and developed a mind of his own. His instability being a warning of too much technological dependence can turn on us. (Another Take)
By the way, me and kconley are taking a narrative approach to our study.