Correction: QuickTime 10 is likely to be released with Mac OS X 10.6 Snow Leopard in the fall, and won't be updated Monday.

At WWDC Monday morning, Apple's Bertrand Serlet came out with guns blazing, not just in support of Snow Leopard, but of Safari and QuickTime, too. Announcing that Safari 4 would leave beta later Monday and that QuickTime would receive a massive overhaul, Serlet introduced new features while taking swipes at both Microsoft and Mozilla.

Safari 4 can be downloaded from CNET for Windows and Mac.

Safari 4 shipping today. (Credit: (Credit: James Martin/CNET))

The senior vice president of OS X software said that QuickTime 10 is now "super efficient" and will support HTTP streaming based on h.264 and AAC, a feature that many competing programs have long offered. The new QuickTime will automatically adjust the playback bit rate, and it will be able to stream through firewalls.

In addition to receiving a major version jump from v7 to v10, the interface has also received a complete refresh. Onscreen controls will disappear when playing back video. The QuickTime "Q" logo will also see a slight redo, changing from its familiar blue to a silver and purple.

Safari 4's Nitro will be the fastest JavaScript engine of any browser on the market, Serlet said. Without describing what kind of benchmarks he was using, he showed a chart indicating that Chrome 2 is 5.3 times faster than Internet Explorer 8, but that Safari 4 is 7.8 times faster. Safari 4 also loads JavaScript three times faster than Safari on the iPhone, Serlet said. HTML 5 audio and video tags will be support in Safari 4, too.

Microsoft was not the only target for Serlet. "The number one cause of crashes," he said, "is browser plug-ins." Mozilla Firefox is the best-known extensible browser, and one new feature in Safari 4 is designed to address the instability that some plug-ins can bring to browsers. Crashes in Safari 4 that are caused by a plug-in will cause only the plug-in to fail. Refresh the page, Serlet said, and the plug-in will reload. "All you need to do is reload that page and that's it. You haven't missed a beat."

I'll be running hands-on tests on Safari and QuickTime later today when they're made available to the public. The update to QuickTime in particular is somewhat surprising, given that Apple had been resistant for years to make any dramatic overhauls to its movie player. If the company can improve its performance, then we may be looking at a heated battle in the video playback market in addition to Web browsers.