"Store" has two meanings -- a place you shop, and a place you keep stuff. Now, Amazon.com wants to live up to both definitions. The company best known as an online bookshop has won admiring reviews for S3, its new Web-based information storage service. Unlike most Web-storage services, however, S3 isn't offered to consumers. Instead, Amazon.com sells storage space to other companies, especially smaller Web startups that can't afford their own mass storage. On Wednesday, Amazon announced that S3 now stores more than 800 million "objects" -- images, documents, and other files -- in the database, and that a growing crowd of companies had signed up to use it.

Bloggers Om Malik and Nick Carr both pronounce themselves impressed. Says Carr: "Because it's the same infrastructure used by Amazon's store, it's exceedingly robust and reliable. And it's cheap." Meanwhile, Malik says that despite being skeptical early on, "the growing number of early-stage start-ups signing up for Amazon S3 indicate[s] that something big is afoot."

Google and Microsoft, of course, are both slated to release Web storage services for consumers which will heat up the market. (A sneak preview of Google's GDrive was inadvertently leaked Monday.) But by getting to market earlier, and focusing on small businesses, Amazon may succeed in carving out a defensible -- and lucrative -- niche. In a seeming irony, even a small division of Microsoft is using Amazon's service to help college students download Microsoft programming tools -- which makes sense when you consider that Microsoft's storage service is targeted at consumers, not businesses like itself.