Links to performance numbers posted wrt various NoSQL solutions:
A top 20 global website announced they have migrated from MySQL to Redis. There will be a keynote and everything. It doesn't say how big the Redis Cluster is, but they serve 100M pages / day, and clock 300k Redis queries / second.
Btw, they mention that MySQL remains as the master data store from which the Redis indexes are generated.
(The reason I don't mention the name of this Redis user is simply I feat my mom is sometimes reading my blog...)