Mac OS X: Snow Leopard

I've got my copy of Snow Leopard pre-ordered, do you?

One delightful change: Snow Leopard takes up less than half the room on a hard disk that Leopard did, and Apple says the average user who upgrades will free up about 7 gigabytes of space. On my 2008-vintage MacBook Pro, I gained back a whopping 14 gigabytes. - Walt Mossberg, Apple Changes Leopard's Spots

When was the last time you heard of a new OS install that took less than the previous version? Apple does more by doing less. Again.