This feature is perhaps bigger news for app developers than end users, but it's an important one nonetheless. Ever used an app that feels really slow, clunky, and unresponsive - almost like a mobile web page? It probably is one! You see, many publishers of apps out there don't actually build real mobile apps. Credit card companies, cell phone carriers, airlines - you know, the sort of companies you kind of live to hate. They're often too lazy / incompetent / cheap to build real native Android applications, and instead rely on what's called WebView. Essentially, WebView allows an app to display a web page. There are legitimate uses for such a feature, obviously, but many developers out there abuse it and construct tiny "shell" apps that are little more than WebView frames.
This is a problem for two reasons. First, web wrapper apps really, really suck. Every time someone publishes a web wrapper app, an adorable kitten angel loses its wings and gets rabies and mauls an innocent fluffy bunny. Second, the current Android WebView is based on the old stock Android WebKit browser, which Google has not updated in something around an eternity. This breaks things. It makes things go slow.
As of Android 4.4, this changes - WebView is now built on Chromium, bringing much-needed support updates for web standards like HTML5, CCS3, and JavaScript. It should also dramatically improve JavaScript performance, since Google's V8 JavaScript Engine is part of Chromium.
This is just one of our many Android 4.4 feature highlights, so keep checking for more as the day goes on. Don't forget to check out our KitKat overview post, either!