iCloud is missing from my Mac

I recently updated all of my software (Mac, iPhone, iTunes) so everything is up-to-date, but I am unable to get iCloud on my Mac. My iPhone and iTunes are both set up to transmit data to my Mac, but when I click on "System Preferences" on my Mac, there is no iCloud icon under the "Internet & Wireless" section. Am I missing something?

My Macbook Pro operating system is OS X version 10.6.8, my iTunes uses version 10.5.2, and my iPhone uses iOS 5.0.1...any suggestions?