This is great, I was really hoping for Redis to take this direction, since keeping everything in memory wasn't great for my current project.

In the same vein, I have an idea about forking memcached and turn it into "memd". Instead of just caching for reads, it would allow writes to be done in memory too, which are asynchronously synced to disk when an item expires, or based on certain conditions (I'm thinking based on both time since last updated, and when enough updates are made). Now obviously, this only works if the data you store isn't all that important, which is probably the case for most web applications.