How to see what files were changed in TimeMachine?

Lion has come out with the tmutil command and the man page shows that it will crawl a specific backup and report very detailed information on your specific backups. The verbs compare, uniquesize, and calculatedrift look most useful if you don't mind the terminal.

I still use BackupLoupe on Lion (as well as on older OS) and have high praise and thanks to the team that built it every time I need to use it. I should probably send them more money, too. It's that good.

It makes it very easy to see what files are taking the most space between backups and also is indispensable for knowing when a specific file has been changed by tracking each time it is saved as a new version going back in time. It works on a local database so you are not crawling the filesystem each and every query - just once each time to collect the deltas for each backup.

Since Time Machine uses hardlinks to store unmodified files (and directories), this would mean that changed files in the latest backup will have a link count of 1 since they are unique. Use this together with find to generate a listing:

find /path/to/your/latest/backup -type f -links 1 -print 

You can use the built in tmutil and GNU gsort:

brew install coreutils

To compare between two specific backups:

cd "/Volumes/TimeMachine/Backups.backupdb/My Mac"
sudo tmutil compare Date1 Date2 | gsort -h -k2

For just the difference between the current backup and the previous backup:

sudo tmutil listbackups | tail -n 2 | awk '{ print "\""$0"\""}' | xargs tmutil compare | gsort -h -k2