If the item protected is a file or a HTML page, a single registration is created. This registration includes the text of the page, if an HTML work, a hash of the registered content, a date/time stamp of when the work was submitted and a My Copyright Number, or MCN, for easy reference.
If the registration is an RSS feed, then all of entries in the feed are indexed separately and all future updates to the feed are picked up automatically on a daily basis. Each entry is given its own registration, including MCN, hash and date stamp.” (From: http://www.plagiarismtoday.com/2007/12/11/myfreecopyright-free-copyright-verification/).
So when I post a blog, I receive an email which looks like this which shows when, where, what time etc. Clearly I am the author.
I am not suggesting that this is the way to protect your work. I am just sharing because it gives me a little sense of security to believe that there is some proof out there, that I am the author of my work. Anyone interested should research the topic for themselves and weigh up the different options before making a decision.
And if I am wrong, or if you find something better, please let me know!