Just four months after its big coming out party at CES, U3 -- a platform for running applications from USB thumb drives -- has already been put on the chopping block by parent SanDisk. The company has decided to join Microsoft in creating a new standard.

U3 was first introduced in 2005, backed by a host of supporting software and hardware vendors. Popular applications including AOL's Winamp, Cerulean Studios' Trillian, McAfee Antivirus and Skype among others were offered in U3 versions to spur its adoption.

SanDisk formed U3 as a separate organization with m-systems, and later became its sole owner after it acquired m-systems in November 2006. The company then made a strong push to promote U3 at CES 2007, announcing an ecosystem of 20,000 U3 software developers.

However, notably missing from the list of U3 backers was Microsoft. The lack of support from Redmond ostensibly spelled doom for the fledgling standard, which required software be installed to launch the U3 applications from USB drives.

Under the terms of an agreement to build a "new experience" for USB drives and flash memory cards, Microsoft will create the interface for the platform, which will be compatible with Windows XP and Windows Vista.

Security will also play a more central role this time around, as SanDisk will offer up its TrustedFlash technology, which is designed to prevent the spread of viruses and malware.

A new entity will be created by Microsoft and SanDisk to support the standard, although details are still being worked out. Consumers won't see the new products until late 2008, the companies said.

"We expect this relationship with Microsoft will raise the overall experience for consumers given Microsoft’s unique software expertise, and grow the momentum given the large community of third-party companies capable of utilizing Microsoft’s technologies," said Yoram Cedar, executive vice president of SanDisk's Mobile Business Unit.

Although U3 has been written off, SanDisk and Microsoft say they will offer a migration path for developers to bring their U3 applications to the new platform. But it's not clear how much support will remain for U3 while the companies are working to finalize the currently-unnamed standard.