Google just launched an new tool called “Google Apps Migration for Microsoft® Exchange” to migrate from Exchange server to Google Apps Premier Edition. The tool or app migrates Exchange mailboxes to the Google cloud called Premier Edition.
Unlike Google Mail and others, Premier Edition is a paid service.
Once migrated, you can access your data anywhere using any computer or smart phone.
You will need to do some work on the MX record to point the incoming mail to Google. Something relatively painless compared to convincing the users of the change.