It appears that the mobile ecosystem won't be the first or even the second to get updates that will allow iCloud functionality - instead it will be Mac OS X Lion and iTunes that make the move first. Of course the difference between the three won't be more than a day in advance of the launch of iOS 5, the mobile operating system coming out with the launch of the iPhone 4S. Updates are expected to be available BEFORE the October 12th launch of iOS 5 for both iTunes and OS X Lion, the exact date being either Monday or Tuesday (two or three days from the day this post is posted.)
This information comes from Japanese Apple blog Macotakara who say they've got a "reliable source" that says OS X Lion Update 10.7.2 as well as iTunes 10.5 will be out early this next week. From what we understand, iTunes 10.5 is still in Beta mode for testers while developers have been given the Gold Master copy of Mac OS X 10.7.2, this meaning that the release is RIGHT around the corner.
NOTE: for all the information you could possibly need at this point on iCloud, head to our SlashGear 101: What is iCloud? post and get educated!
October 12th will be the release of both iOS 5 with iCloud support AND the iPhone 4S (plus the other newly price-adjusted iPhone collection) in stores. The three biggest mobile carriers in the USA and Apple have reported that iPhone 4S pre-order stock is sold out, so if you're going to be amongst those getting one on October 12th, you're going to have to head to the front-door camp. Meanwhile we expect iOS 5 to be pushed to all other compatible Apple devices sometime this week - hopefully, again, the 12th!