Continuing on with its rundown of OS X 10.10 Yosemite, Apple's Craig Federighi just introduced MailDrop. The new feature addresses a "fundamental problem with email" by allowing users to send large files over email, via iCloud.
As it sits now, users get the error 'Cannot send message using the server Mail' when they go to send larger hi-resolution images or HD video via the Mail app in OS X. But MailDrop fixes this by allowing you to send files via iCloud...