With iTunes 10.3 and iOS 4.3.3 you can enable certain iCloud features from tomorrow, today.
On your devices using iOS 4.3.3, open the Settings app and select Store to turn on automatic downloads for music, books, and apps as you desire. On your computers using iTunes 10.3 or later, use the Store tab in Preferences and check what you want in the Automatic Downloads section.
Too bad there is still not an option that keeps iPhone apps from automatically downloading to your iPad.
(Via the amiable Rick Stawarz.)