Distributed network RAID

[Bart Silverstrim]

I recall seeing that this was possible, and wondered if someone on the 
list can help with pointers and/or experiences trying it...

I remember seeing a way to create a filesystem on two computers such 
that you have two partitions mirrored over the network for increased 
reliability.

For example, I would be able to take /home on machine 1 and any changes 
I make will automatically migrate over to machine 2's /home, then if 
machine 1 dies for some reason I can log into machine 2 and my data 
would be intact until I can bring up machine 1 again.

Anyone else recall seeing this, or even better, configure something like 
this before?