Self Updating Websites change themselves depending on the date, or some other factor. This could be a band website, which has a gig list with the current month already selected when someone views that page.
In E Commerce websites, things such as order time verses delivery dates available mean that you do not manually need to change the date an order will be delivered every day.
Another example would be an accountant's website with a financial diary with the upcoming important tax dates at the top of the page.
Another reason for using a self updating website technology is that the search engines like websites which change regularly. It seems to them that the website is being worked on constantly; therefore, it will have current and relevant information. This is all part of The Love Principal.