This page used to have a non-descript image as the background for its Acrosstic, but the poem isn't about mere transparency in a piece of glass. Instead, it is much more about transparency in the cutting edge of technology, computer software. There is far too much software out there that does things its users would not agree with if they knew about it, and many of it is counterproductive. Proprietary software is usually software that we can not see the original code for, and so we users have to judge its performance based on the behavior it exhibits.
Of course there are ways this can be looked into, for instance with a program called WireShark, which intercepts all communications in and out of a piece of software, allowing us to figure out if it sneakily sends a request or data to certain not too savvy locations. But the point is that many programs try to push us into storing our data on the Web, where we have to trust the companies to keep it safe.