Alpine Linux is a run-from RAM linux distribution. Its original target was small appliances like routers, VPN gateways, or embedded x86 devices. However, it supports hosting other Linux guest OSes under VServer control, making it an attractive hosting solution as well.
It can boot from a 1GB USB stick, CDrom, or hard drive. Packages compiled against uClibc are pulled into RAM for execution. All packages are compiled with grsecurity patches and SSP to provide a secure runtime environment. The lbu backup system stores all changes to /etc (and custom changes) to the boot media, making system disaster recovery brain-dead simple.
The name "Alpine" stands for A Linux Powered Integrated Network Engine. Alpine is a "swiss-army-knife" of Linux distributions; with a focus on security.