I love Sublime Text 2 and purchased it a few days after trying it out, and have been using it a great deal for a few months. After using it for just a few minutes I immediately began to draw the similarities between it and Google Chrome. Everything from the way you drag tabs around, the speed of the program, the text rendering, the smooth scrolling, and even the cursor fading in and out smoothly, instead of binary on/off, as if it were a CSS3 animation keyframe. And last but not least but the fact that it works flawlessly across the three major platforms!
I know it is a closed source product, I will make the broad claim that Sublime Text 2 uses webkit internally to render its user interface.

I do not believe that Sublime Text uses webkit at all. My understanding is that Jon wrote a custom GUI in C++.

If you look at how the themes are implemented you’ll see that it is not CSS used for styling, but something different. Additionally, I’ve seen a number of different entries in the dev changelog (sublimetext.com/dev) that indicate he has worked on tweaking things like sub-pixel aliasing on OS X and using Pango for font rendering in Linux. A further differentiator is that Sublime uses Python for its API rather than Javascript.

And no gpu in sight