"Offering a generic SharePoint experience won't really satisfy most users," Gilbert says.

Microsoft is locking down the with strict requirements for applications to be listed. Applications will have to pass the "Microsoft Platform Ready" test, which will become available when Office 365 exits beta and enters commercial availability. "All software and services solutions will be subject to Microsoft evaluation to make sure those solutions add value to Office 365 customers," Microsoft says.

This approach, apparently more strict than what you'd see with mobile phone app stores, makes sense given that these applications and services will be targeted at corporate users.

It's probably too early to know how much of an impact the marketplace will have on real-world implementations.

"It's certainly a strong move by Microsoft, though it seems to be mostly implementation partners at this point," says Forrester analyst Ted Schadler. "It will get much more interesting once people build tight integrations of their own cloud services and start customizing apps for SharePoint in the cloud."