Web Standards: The WebKit May Not Be All It Can Be
The problem is multi-fold. As a developer, if you utilize WebKit in your own applications, you are the one who is responsible for keeping it up to date. It's not just possible, it's extremely likely that users could have multiple WebKit versions on their computers, each of which having its own update technology, or the lack thereof.
Microsoft recently detailed the new features that its Internet Explorer 9 would have, which included an advance in its Trident rendering engine which speeds up and enhances the user experience. What really stood out was its idea of "standards interoperability," which literally translates to mean "same markup."
This would mean that every web browser would display (render) the same web page the same way, adhering to a standard that, well, doesn't yet exist. WebKit does not do that--it renders differently depending on the sites that are being visited, and the browser that is being used, and the device that it is running on. Standards are great when they are adhered to, but that, truly, is what it will take to make the vision of the web of the future truly work.