About a year ago I wrote about how use mod_header with Apache 1.3x to send Cache-control headers. It worked so well that I want to configure my Apache 2.x servers to send the same headers. It's even simpler with Apache 2.x since mod_expires is included in most default installs. Here's what I did.
I added a configuration directive for the main server configuration (inside the Directory block) which sends the Cache-control header for common graphics.