But Microsoft views SSDS as not only a cloud database, but as the data foundation for an entire ecosystem. With that scope of mission in mind, there are other incumbents. One is Intuit's QuickBase. Available since 2000, Intuit claims more than 225,000 customers of the service, which is aimed at business users looking to easily build and connect to other SaaS applications (in the QuickBase ecosystem) without the need for heavy programming skills.

Trying to grow beyond its CRM-on-demand roots, Salesforce.com unveiled the similar Force.com platform last fall. Force.com lets users store data for retrieval and usage by a small but growing number of apps, including some from third parties.

The best-known platform competitor to Microsoft and SSDS, however, is crosstown rival Amazon.com.

Yeah, I'd heard SSDS is just a belated, 'me-too' offering to compete with Amazon.

Sort of, though please disregard any comparisons to Amazon.com's S3 online storage service. Despite being a big hit with the Web 2.0 crowd, S3 is fairly crude and doesn't really offer any database features.

The better comparison is with Amazon's still-in-beta Web-based database, called SimpleDB.

SimpleDB will offer basic, easy-to-use data processing features that don't require users to have DBA skills; easy scalability; a subscription model; and strong ties to other cloud-based infrastructure -- in Amazon's case, its application hosting service, EC2.

Sounds nearly identical to SSDS.

For now it does, concedes Microsoft SQL Server architect Soumitra Sengupta, in a Monday posting on the SSDS Team blog.

The difference, writes Sengupta, is that Microsoft "has chosen to expose a very simple slice" of SSDS' potential capabilities -- unlike SimpleDB, with which, he implies, What You See (Now) Is What You Get.

With SSDS, "we will be refreshing the service quite frequently as we understand our user scenarios better. So you can expect to see more capabilities of the Data Platform to start showing up in our service over time. What we announced here is just a starting point, our destination remains the extension of our Data Platform to the cloud... In the meantime, can we agree that SSDS is simple but it is not SimpleDB."

Web 2.0 loves MySQL. So is the open-source database Microsoft's real target with SSDS?

Maybe, though Microsoft hasn't said as much. For MySQL's part, it says it has allowed partners to host MySQL for more than three years. But it hasn't waded into cloud databases yet, according to vice-president for marketing, Zack Urlocker.

"We aren't ready to make any new announcements at this time, but it's an area that's being evaluated as we integrate with Sun Microsystems," Urlocker wrote in an e-mail, tantalizingly adding, "Sun certainly has the expertise in massive scale and cloud computing that could make for an interesting story."

Will using SSDS lock me into a Microsoft infrastructure?

Not in an obvious way, as SSDS seems to support key, relevant standards, SOAP and REST being the most important. On the other hand, Microsoft does hint that at some favoritism in its FAQ: "We will provide a great experience working with Microsoft products and development tools. In addition, we will provide support for development on other platforms and will invest in a strong development ecosystem around our service." In practice, it's likely SSDS will for a long time mostly be taken up by users who are already heavy into Microsoft.

What are the disadvantages of using SSDS?

Since information remains scarce, we can only infer that SSDS will at the least share the typical issues associated with SaaS apps. While startup costs are low, larger users may find the cost of subscribing to SSDS over time eclipsing the cost of running SQL Server in-house. That's especially true if you include the bandwidth costs associated with relying on SSDS.

Also, sophisticated users may find SSDS' features too sparse. For instance, users can't store videos and other large unstructured data objects (BLOBs) inside SSDS -- a common advantage of relational databases. Finally, there is the lack of control over the security and availability of your data, despite Microsoft's Service Level Agreements (SLAs). However, Microsoft says that it will create an on-premise version of SSDS that can ameliorate those concerns.