According to a report by Mac Rumors, developers are already playing around with early builds of the next major version of Safari.

Safari 4 will include the SquirrelFish JavaScript engine being developed by the WebKit team. Apple is touting SquirrelFish as "the fastest implementation of JavaScript ever." In addition, Safari 4 will also include a feature to create site-specific browsers, or SSBs, from any webpage. The functionality is not unlike that offered by Mozilla Labs' Prism project or the highly-regarded Fluid for Mac OS X, which create a desktop app that is basically a browser with minimal UI to directly access a web-based app. And, Safari should incorporate CSS-based graphics improvements by the WebKit team, including CCS-based gradients, masks, and reflections.

These features make perfect sense in relation to not only increased use of Web2.0 apps like Google Mail or Flickr, but with the new MobileMe service that Apple announced yesterday. Given its reliance on JavaScript to mimic desktop app functionality, eking out every bit of performance from the JavaScript engine is a must for reasonable performance. And a site-specific browser for accessing MobileMe's services can make an even more transparent user experience. If cloud computing becomes the standard, the transition for Mac users will be seamless. The CSS-based graphics simplify many common effects and improve performance by relying on rendering code compiled into the browser. It brings a richer graphical experience to web apps akin to Apple's polish on the desktop.

Though we've heard that Snow Leopard should ship in about a year, Safari 4 could come much sooner. Mac Rumors notes that there are multiple versions "specifically for Windows, Tiger and Leopard." The projected performance improvements of JavaScript alone would be appreciated by MobileMe users. All in all, Safari looks to gain yet more speed and will be ready for the cloud as more people move their data online.