Can you point me to any reasonably-priced database systems that allow me to execute SQL queries against a cluster of shared-nothing machines running commodity hardware? I'm not interested in paying $20-100K/TB/year for Vertica and friends.
SQL can be great if you have vast amounts of money or if your data can fit onto a single machine. When neither of those things are true though, nosql DBs become important.
If it has to have built-in sharding then I can't think of anything off-hand.
Auto sharding, shared nothing, SQL support, it does a pretty good job of things.