Microsoft on Wednesday said it began testing Live Mesh a service that blends desktop computing with the increasingly popular web-based social computing trend.

It is in many ways Microsoft’s attempt to reaffirm the relevance of Windows in a world where a growing amount of casual computing is occurring on the web rather than at the desktop.

Live Mesh is for the most part a file-sharing and file-synchronizing service that allows users to access desktop files on the web using multiple PCs or other Internet-capable devices.

The technology, which is currently in a limited test phase, is partly a marriage of Windows Live, a set of web-based applications, and SharePoint a web-based collaboration technology.

“This is a next logical move for Microsoft in its Windows Live strategy,” said James Staten, principal analyst with Forrester Research. “Mesh allows file sharing to occur as a lighter weight experience than SharePoint.”

With Live Mesh users can store, access, and share desktop files on the web. An automatic synchronization tool can update the web-based files with changes made to files stored on multiple PCs.

“Microsoft is marketing a lot about the value of putting files in the cloud so you can easily sync them with other devices,” Mr. Staten said. “But the bulk of use of this will likely be for sharing files on Internet social networking sites and between colleagues and friends.”

Beyond file-sharing and synchronization, the announcement hinted at a number of other applications including remote access to your desktop via Live Mesh.

Laura DiDio, research fellow at Yankee Group, found some of the more futuristic aspects of the announcement lacking in clarity.

“In many ways this announcement was too vague for a product ticketed for consumers,” she said. “I wish Microsoft would steal a page out of Apple’s playbook and make the details of these products more accessible to consumers.”