Following last week's celeb-photo-hacking-scandal, Apple has started sending email notifications that warn people that their iCloud accounts have been accessed from web. This is the first step to what we've been told will be a more secure iCloud future.
Now when you login to your account from a web browser—or when somebody else does—you'll get an email letting you know that someone tried to get into your account. It's a very effective way of detecting unauthorized access, even if it's only a warning that you account has been accessed after the fact. Previously, Apple sent notifications when your Apple ID was used to login to FaceTime and iMessage, but not for iCloud.
In hindsight, this type of notification is basic common sense so much so that you could be forgiven for thinking this has been happening all along. That said, Apple's obviously got a long way to go before it's making sure your accounts are truly safe. [MacRumors]