Database.com is the same relational database system that powers Salesforce.com, allowing developers to take advantage of the company's infrastructure and scalability. Database scalability is a major issue for today's Web applications, and Database.com is the latest in a long line of solutions. Given Salesforce.com's track record, it will probably be an appealing one for cloud developers.
The database currently contains more than 20 billion records and delivers more than 25 billion transactions per quarter with a response time averaging less than 300 milliseconds.