I knew something was up this morning when my wife sent me a Message saying that she had received an email from Apple about exceeding 5 GB of storage and functions would stop working after September 30, 2013 if she continued to exceed that amount. There's a reason for this: former MobileMe customers (those who may have a .mac or .me email account) received a 20 GB complimentary storage upgrade when they moved to iCloud. That upgrade expires next Monday -- September 30, 2013.
To keep things running the way they have since 2011 when the migration from MobileMe to iCloud occurred, you'll need to either reduce the amount of storage you're using or buy one of Apple's storage plans. Those plans include 20 GB more space (25 GB tot