An interesting article in the New York Tines online by Derrick Harris of GigaOM outlined the release of some customers using Clustrix webscale SQL database, namely, Box.net, AOL, PhotoBox, and iOffer.
Clustrix launched in early May with the claim that it’s DB technology, which features MySQL like transactionality and reliability, could scale to billions of entries. All four customers announced by Clustrix in the press release announced that this was the case.
Clustrix provide this as an appliance as an option for online services that do not want to have to invest time and effort in figuring out how to a) shard their data for better performance or b) move to something relatively new such as MongDB, or Cassandra.
Further details (which are worth reading) can be found on the original post on GigaOM.