CloudFront support

What is the best way to handle cache invalidation? Is this the correct process?

1. Check hash to see if file has changed and needs to be uploaded.
2. If changed or missing on remote, push file.
3. If this is the first push of the file then we are done, move on to next file.
4. If the file had already existed on S3, add to list of files to invalidate.
5. At the end of syncing, send cache invalidation message to S3. (Check on message length limits, there are several with SDB/EC2, and probably for CloudFront)