Apple has quietly implemented in-transit encryption for iCloud emails. Emails sent to or from an @icloud.com or @me.com address are now encrypted. Previously Apple only encrypted emails sent between iCloud addresses. The encryption will help to secure emails moving between servers from snooping, particularly on the part of the government.
The encryption was picked up by, of all people, Google. While iCloud emails likely don't consitute a huge percentage of the emails sent and received through Gmail, a full 73% of the Gmail's outbound messages are encrypted, while 56% of those received are. In the past six months the encryption rate has roughly doubled on both ends.
It's good to see Apple taking steps to ensure the privacy of its users communications. How else would you like to see Apple address privacy on the web?