I've got a 128gb SSD in my 2008 Alu MacBook. I'm running Lion 10.7.1. When I open Disk Utility, it shows I've used approx half of my OS X partition - the same when I open Activity monitor. When I "get info" on Macintosh HD, it shows I've used much less (What I believe to be a more accurate amount). I've got the WhatSize app to show my drive usage. As I'm running on a small partition, I disabled the hibernate option to save disk space. Wondering if updating to 10.7.1 has re-enabled this? Is there any other options to check?