Preroll.. true, it does the above cache clearing you mentioned.
Primarily, what it does is this: "All Java® objects are stored on the BlackBerry smartphone in random access memory (RAM) or flash memory. Normally, when Java objects are no longer needed, the memory assigned to that object is released to be overwritten by new data. With the memory cleaner turned on, the BlackBerry® Java® Virtual Machine (JVM) overwrites the memory using zeroes before it is released. As a result, data cannot be retrieved from the memory chips."
More importantly, I'd suggest you ask your IT guys to read this:
Article ID: KB19371
BlackBerry smartphones with content protection and memory cleaner turned on may experience slow performance
In short, what Memory Cleaner primarily does is performs a zero-overwrite of already deleted memory, to a higher government specification. For the average user that doesn't work for the CIA, FBI, MI5 or is not a prOn or drug dealer, it's a worthless process hog.