Engadget is reporting that Apple will be holding a 'Back to the Mac' event on October 20.
It is likely that this event will announce Apple's new notebook line as the MacBook Pro line of notebooks have been needing a refresh of hardware. Shown on the PR image above, Apple may also be planning to announce a new version of OS X (possible 'Lion'?).
The event will be held in Cupertino at 10 AM PT on October 20. You can be sure that Engadget will have a live feed to keep you up to date.