In order for iCloud to be useful for us it needs to work on Snow Leopard and Leopard machines and also needs to sync Mail rules and Keychains, just like MobileMe does now.
icloud is not a replacement for mobile me. If you need features that are no more, you need replacement services.
And iCloud is exclusive only to those owners of EITHER ios5 AND/OR LION.
If you all so badly want to jump across the iCloud, all you need is a 189 US$ iPod touch 8GB or even a used 3rd gen touch as the cheapest device that lets you enjoy ALL icloud features, including keeping your @me.com adress forever. You do not NEED a Mac for that. And you do not WANT one, if you know this : Some features are also not even working or present in a Mac, yes not even in Lion :
iwork document syncing is not even supported in Lion with iwork installed, it is exclusive to iOS5 devices alone, just only to let you know what you think you "miss" . icloud syncing between Macs and iOS5 is basically only Mail,Adresses and iCals .
And the iPod touch by the way is not only a mp3/video player. It is a full blown Mini-Mac in your pocket with iMovie and iwork, facetime, mail , safari, dictionary, imessage, ibooks, and apps and games and all you wish to ever need. So just get that. You might use your old Desktop or Laptop boxes for "other stuff", but you do not need them for iCloud.
Go over to the iCloud forums for Mac. There are people that wished they never signed up for it, because basically it is pointless if you only have a Mac. iCloud only shows what it really has to offer on iOS5 and with icloud-enabled apps on it.