CRZ's the only admitted Mac user on this board who'd have any idea who Raskin was, I think. And he didn't say anything.
The GUI concept dates back to the Xerox PARC (Palo Alto Research Center) in the early seventies and even before that. Douglas Englebart "invented" the mouse around 1962 he also had the idea of a "windowed computer environment." And Ivan Sutherland created Sketchpad around 1968, which pioneered the idea of moving things around a computer display.
The Xerox PARC lab created the first fully-functional GUI environment around 1974 with their Alto computer. They continued to refine it over the next few years.
Raskin did his master's thesis on WYSIWYG computing in 1967, so he was probably aware of the work of Englebart and Sutherland. He put the GUI bug (via mentioning the PARC work) in Jobs' ear as early as 1976, but the first visit of Apple employees to the Xerox facility didn't happen until Apple sold a bunch of stock to Xerox in 1979.
The rest, as they say, is history.
That's not to say that Raskin wasn't a pioneer. He certainly was. Without his work Mac wouldn't have been as successful as it was. He was truly one of the visionaries and will be missed.
I believe this change was implemented by Twitter's Creative Director Douglas Bowman (http://www.stopdesign.com) as well as the new Twitter front page and default theme. All changes for the better, I believe.