Mike Torres, MSN Spaces web experience program manager, says in a comment that disk space is not free and therefore Micr*soft couldn't support more than 10MB of space for 150 million people.

True enough! But then how does Gmail support 1GB of space? Both Gmail and MSN Spaces are free, ad supported web apps that will be used by millions yet Gmail allows 1GB and MSN Spaces only allows 10MB. Methinks something is amiss here unless MSN can't get the same ad revenue that Google does which I suppose is possible.