Apple has updated its Developer Center to include pages
Apple has included a download link to test the features of iPhoto 9.2 Photo Stream on a separate development environment. Many of these features are devoted to the Lion and clearly Apple has told developers to download the OS X Developer Preview version if they want to test the functionality iCloud.
iPhoto update will replace your current version of iPhoto.
iPhoto Library that there is no version of iPhoto will open with this. For this reason, it is recommended you work on the test/development system only when using this release.
You will not be able to restore the system to a previous version of iPhoto without doing a "clean install" on Mac OS X and reinstall iPhoto, either from the original installation DVD or by downloading from the Mac App Store.
iCloud Control Panel for Windows is also available in order to activate the "Photo Stream, Contacts, and Calendar" on the PC through iCloud. New accounts can be set in the iOS iCloud 5 setup assistant or the Settings app, the Lion. iCloud can be activated from the Internet accounts in System Preferences, Developer Preview 4 may be needed for this. Once installed and enabled on all devices, Apple will ask developers to test new features and take advantage of the API number in the Lion and IOS 5.