It seems Apple have sent out welcome emails to Apple iCloud already, and a broken link in the email would suggest it was by accident. Amoungst the users to get their hands on an email were AppleInsider who posted a screenshot of the email.
The welcome email starts by telling users that their email will become their Apple ID for accessing their iCloud account and for setting up the iCloud on their iPhone, iPad, iPod touch, Mac, and PC. Followed by a link with instructions on how to do so. The rest of the email summarizes the the capabilities of iCloud.
Apple iCloud is expected to be revealed at the Apple press event next Tuesday, October 4.