AppleInsider reports that Apple is preparing for a big event during the last week of October.

Most likely Apple will finally launch the delayed OS X Leopard. Rumor has it that the shipping date of Leopard would be October 26th.

Amazon.com is taking pre-orders for OS X for $129 since June.
Amazon.com also guesses an October release date for OS X 10.5.

Steve Jobs revealed the final feature set of the new OS X version at the WWDC in June.
Apple says that you get more than 300 inventions with this 64-bit OS X update. The highlights are the new cool desktop with stacks, Finder with music cover browser, Time Machine backup, Quick look and the new iChat.
More details on AppleInsider.