When Mac OS X Lion was first announced, it was also mentioned that unlike the previous incarnations of the operating system, it will not be available in CD format, which meant that users who wanted to install OS X Lion will either have to download it or get it on a USB stick, which costs about double what the downloadable version costs. While I can't speak for the masses, having a USB stick containing the operating system will be handy when you want to format the computer and require a reinstall.
Ubergizmo, Apple reportedly shipping USB sticks containing OS X Lion
