I just upgraded to iOS5.1, and I used iTunes on my Mac to do it. iTunes downloaded a 805MB file that it used to upgrade the iPhone. The issue is that after it applied the update, it didn't remove the 805 MB file. I only have 4 GB free on my SSD hard drive, so I would rather not have some old iPhone update hidden someplace. (Looking back, I should have done the update right from my phone since it was an 187 MB delta update... and it wouldn't have gone to my MacBook hard drive.) Thanks!