According to Linux Magazine, DRBD will soon be merged into the official Linux Kernel!
What is DRBD and why do you care?
From http://www.drbd.org/:
"DRBD® refers to block devices designed as a building block to form high availability (HA) clusters. This is done by mirroring a whole block device via an assigned network. DRBD can be understood as network based raid-1."
Pretty damn cool if you ask me.