iCloud support is limited to relatively new Macs able to at least run Lion. Practically speaking, Mountain Lion.
Apple is kinder to the Windows world. The iCloud Control Panel will run on Outlook 2007 or later on any old OS.
I suppose they don't have the same sales incentives on the Windows platform. In any event, it seems to work very much like the old MobileMe Control Panel, at least when it comes to Contacts. I installed it on a Win 7 laptop running Outlook 2007 that syncs to Exchange Server and I now have full access to my iPhone/Mac Contacts.
It works by creating a new account, separate from the Exchange account. There are few install options -- you have to sync Calendar, Contacts and Reminders (but not Notes). Just like MobileMe  (I suspect some shared code). It also creates an IMAP account.
I had some glitches on installation and had to fiddle with restarting both the Control Panel and Outlook 2007, but now it seems stable. I didn't want the IMAP service so I canceled out of the credentials prompt and deleted the IMAP account.
There's no way to turn off Reminders, so I now sync my iPhone reminders in some puzzling ways -- basically via ActiveSync/Exchange for one set of reminders, via this method for the iCloud set. Weird.
Contacts is what I was interested in and it seems to work. Since Outlook allows only one Group per Contact, and iCloud allows many  there are potential problems related to Group assignment. In the case of MobileMe this didn't seem to break anything.
It's great to have all my Contacts at hand, and to able to quickly add to them. As an extra bennie, I get to use Outlook's Contact views. They are old and complex, but they are far more powerful than anything Apple gives me.
 Group relationships are kind of messed up between iOS and OS X, but Apple has bigger problems.
 At one time MobileMe Control Panel could work with Outlook/Exchange, but then it coulnd't -- which made things hard. This version can, perhaps because it creates a new local account.