Apple’s long awaited update for its operating system is finally out, Mac OS X 10.7 Lion is on sale at Apple App store. The update will cost you $30 and you can download this update for Apple previous Mac OS X 10.6 Snow leopard from the Apple app store.
Mac OS X 10.7 shows significant improvements under the hood along with some visual enhancements.

Rosetta is not included with this update and ppc application won’t work any more. If you rely in you daily work on any ppc applications do not upgrade your Mac.

You can upgrade to Apple Mac OS X Lion only from the previous Mac OS X version 10.6 Snow leopard. Direct upgrade from 10.5 is not supported.

Seems like build 10A432 is the Gold Master of Mac OS X 10.6 Snow Leopard from Apple. This build will be soon released to manufacturers and probably will leak on the torrent trackers and sites. Several sources confirmed this rumor to popular mac rumor websites such as macrumors.com.
Mac OS X 10.6 Snow Leopard will be released on September and will be cost 29$ to upgrade for all Mac OS X 10. Leopard users.
This will be the first Apple operating system running 64 bit kernel.