WebKit, the rendering engine used by both Chrome and Safari, is currently undergoing major redevelopment in order to support per-tab processes and out-of-process plug-ins by default. In one smooth move, Apple will be able to bring Chrome-like speed and security to its Safari browser.

Don't be fooled by its rather grand-sounding name of "WebKit2," however. This is more of an update than an upgrade. Basically, WebKit is being split into UI Processes and Web Processes. Each tab will become a UI Process, and presumably, so will add-ons and extensions. This change will bring the usual benefits of stability, security, and speed-ups from multi-core processors. WebKit2 will also implement a non-blocking API that is "mostly platform agnostic," resulting in a more flexible browser and better cross-platform extension compatibility.

The new WebKit2 will operate a lot like Chrome does today, only in theory, faster. With the split-process logic injected at a much lower level, it wouldn't be a surprise to see Safari out-perform Chrome. It will be quite interesting to see whether Google moves to support WebKit2, or indeed builds it into their browser.

I can't help wonder why Google implemented the split-process logic in Chrome, rather than being the major exponent of WebKit2, though. A competitive edge doesn't make much sense when it's all open-source anyway.

The WebKit2 patches are due to hit at any moment now, but I don't know when we'll see a version of Safari -- or indeed, Chrome -- running the new layout engine.