The " -- " is a new way of creating a comma. You know a comma creates a space or pause, right? Read it out loud: "To help build the converged infrastructure of tomorrow, today." Does that make sense? I would guestimate that the visual impact of the " -- " in print is one of the reasons it's becoming more common, and also -- texting/emailing is changing how people use punctuation.

To help build today the most modern converged infrastructure today - one that we would expect to be built only in the future - the one that we would not actually expect to be built today, but rather tomorrow.