It is in OS X and was in iOS beta's but was pulled for the GM. You can still get keychain syncing between Mac's until iOS brings it back once everything is finally public. You should be asked for a four digit code when first initializing the feature in iCloud settings. It may prompt you for a security setting or such change, don't, just keep following it through. If it is waiting for authorization, go to your other Mac with the same iCloud account and there should be a notification. Dismiss or ok it, and your "Mac's" should be set. Until iOS 7.x.x releases it for the public, all we can do for now. I've got it synced between my Mac Pro, MacBook Air and Mac Mini, it's just like the old .Mac "Keychain Syncing" with more robust features akin to "1Password", a much welcomed return.
Safari in 10.9 will ask to save any credit cards you use as well as your logins between systems, which can all be accessed securely in your browser preferences.