This is great news if, like this site, you are running statically hosted sites from an S3 bucket. In the past you could hack your way to Gzipped files by precompressing content in your workflow before uploading to S3 but... ugh.
Even dynamic sites that were previously Gzipping files on the fly can now reduce code complexity, compute cycles, etc. and let CloudFront handle that for you at the edge.
The functionality is free, simply enable it in your distribution's behaviours where appropriate and you are done. It will likely even save you money as your bandwidth costs will decrease if you were serving uncompressed static content in the past.