Perhaps not ready for primetime, but for your consideration, this project's readme:
UPDATE: please note that this is just a toy. A proper "redis-cluster" is on the official Redis roadmap. There's also the twine project to consider.
Redis supports master-slave (1:N) replication but does not support automatic failover. That is, if the master "goes down" for any reason, your sysadmin (read: you) has to reconfigure one of the Redis slaves to be the new master.
One could use monit or God or whatever alongside redis-cli to check if a host is up, then send the other hosts a SLAVEOF command to reconfigure the cluster around a new master.
I created a Python script that does this instead. It only took an hour to do so no big loss. OK, I didn't think of using redis-cli initially :)
Perhaps this project could at least be a part of the infrastructure (perhaps in concept only) for the forthcoming "redis-cluster" project.
The original mailing list thread discusses the origins of this project a bit.