I received an email from MM that boils down to:
1. MM will be free until 30 Jun 2012.
2. On 1 Jul 2012, MM disappears.
3. iCloud will launch this Fall with a minimum of iOS 5 for moble devices and Mac OS 10.7 for Macs being required.
4. Those MM members meeting the requirements in 3 above will be able to move their MM email address(es) to iCloud.