iCloud無料の条件とは？

MobileMe利用者にはこんなメールが来たはず。

Dear MobileMe member,  

We'd like to share some exciting news with you about iCloud — Apple’s upcoming cloud service, which stores your content and wirelessly pushes it to your devices. iCloud integrates seamlessly with your apps, so everything happens automatically. Available this fall, iCloud is free for iOS 5 and OS X Lion users. 

What does this mean for you as a MobileMe member?
When you sign up for iCloud, you'll be able to keep your MobileMe email address and move your mail, contacts, calendars, and bookmarks to the new service.
Your MobileMe subscription will be automatically extended through June 30, 2012, at no additional charge. After that date, MobileMe will no longer be available.
When iCloud becomes available this fall, we will provide more details and instructions on how to make the move. In the meantime, we encourage you to learn more about iCloud. 

Sincerely, 
The MobileMe Team 

つまり、iOS5にバージョンアップして、Lionに切り替えろよ、ということ？ (Windows利用者は知らん、と)