Those familiar with the ongoing development of Mac OS X 10.6, aka Snow Leopard, are telling AppleInsider that WWDC '09 will be the time and place for a smash-preview of the new OS. According to the leak, Apple is holding the best for last, keeping major UI changes out of developer builds for an exciting preview presentation this summer.

Citing people familiar with Apple's plans, the aforementioned news source says that “the next developer build of the software will unleash some of the biggest changes to the next-gen OS since Apple first previewed the software to developers at last June's Worldwide Developers Conference [...] The concern is that those changes will inevitably leak on the web, and therefore they may preserve them for an official demonstration during the company's spring Worldwide Developers Conference,” reads the report.

The most important of changes planned for unveiling at the next edition of the event is “a striking overhaul to the Mac OS X user interface, which is expected to surrender its platinum theme.” According to the people speaking to AppleInsider, the Mac maker has reportedly been working on the new interface since the beginning of development. Ongoing public belief has been that Snow Leopard will do without any radical external changes in favor of under-the-hoot improvements. The site goes to post some story highlights, such as,

- Next Snow Leopard builds to include big changes
- Snow Leopard to be wrapped in new interface ahead of launch
- WWDC to offer finalized preview, release date
- Snow Leopard to hit retail within two months of WWDC.

Reportedly, the same people have leaked information in regards to an upcoming iPhone OS 3 beta, which allegedly activates the live Push Notification support. Back to Snow Leopard, Apple is believed to require approximately two months' time from the public preview to polish up Snow Leopard. This would push the new OS to an August retail release, assuming WWDC takes place in June, the report concludes.