Title text: It's fun to watch browsers fumblingly recapitulate the history of window management. Someday we'll have xmonad as a Firefox extension.
This comic is a parody of the "Get a Mac" (also known as "I'm a Mac" or "Mac vs. PC") ad campaign for the Mac brand of computers. The ads personified the Mac and their competitors, the PC. The ads poked fun at the PC's terrible function while paying attention to the Mac's unique features. Each ad started with the duo introducing themselves as "I'm a Mac..." "... and I'm a PC."
The comic, however, presents them as identical to each other, since very much everything nowadays is done through browsers due to the proliferation of cloud computing. In essence, using the same browser to visit the same website among different operating systems would give you an experience that is very much the same. Additionally, this comic could also be taken as a riff on xkcd's simplistic style, as they are literally identical in character design.
The title text refers to window management, which is software that controls windows on computers. xmonad is one such program, and Randall says that eventually it will be an extension usable with the browser Firefox. What makes it somewhat unusual (and thus worth mentioning) is that it is a wikipedia:tiling window manager, meaning it automatically arranges and resizes newly opened program windows to fit a grid. This is especially useful on large screens.
Google Chrome OS is this concept taken literally: every program that can be installed by the default method actually is a "web app" running in, obviously, the Chrome browser. Though no direct reference is made, the release of the first Chromebooks predates this comic by only two months, and it's hard to believe that Randall could have missed it.
- Mac: I'm a Mac
- PC: And I'm a PC.
- Mac and PC: And since you do everything through a browser now, we're pretty indistinguishable.