For the paranoid kind, you can always print a few pages full of characters to overwrite the printer's cache.
I think SecurePrint is because some printers store all pages that have ever been printed?
Any printer has cache, some heavy duty enterprise level printers come with a harddrive. Regardless of the printer, it is reasonable to assume some of the data you have printed may still be within the printer's memory until you override it. SecurePrint ensures that data is encrypted.
It is also useful for network printer, which require you to expose the data to print to your entire network.
