Users who haven't upgraded their Macs to Snow Leopard, let alone OS X Lion, may be in luck: Apple is reportedly offering a free copy of Snow Leopard to push users toward iCloud.
Macgasm reports that some MobileMe customers are receiving email offers to receive a free DVD of OS X 10.6 Snow Leopard. After they upgrade, the report says, those users are then asked to purchase OS X 10.7.3 Lion and sign up for iCloud.
Users are asked to log in to Mobile.Me at this link, then fill in their address information. Users should then receive an email saying, "Snow Leopard is on the way," Macgasm commenters reported.