Microsoft has received a patent for a system that automatically notifies users of its software when there is a change to their application's privacy policies, according to documents released Tuesday by the federal patent office.

The patented system automatically informs users if there is a change to the way in which Microsoft intends to use personal data embedded in the application, and then prompts them to consent to the change. It also prevents the application from accessing the user's personal information or data unless the consent is given.

Online privacy is expected to become a bigger issue for computer users as more and more applications migrate from the desktop to the Web. Earlier this week, Microsoft released a number of updates to its Windows Live platform -- an array of hosted offerings that include e-mail, instant messaging, and blogging applications. Google offers a hosted application package called Google Apps.

Microsoft's new patent also defines ways in which users' individual privacy preferences can be associated with the applications they use, according to documents posted on the U.S. Patent and Trade Office's Web site. The patent, for "Privacy Policy Change Notification," additionally describes a way to automatically check and see if an application's privacy policies have changed since it was last accessed by an individual user.

While the system sounds like a convenience to the end user, some Microsoft watchers are worried the company could use it to browbeat customers into either accepting more relaxed privacy policies are having access to their online applications cut off.

"Imagine if I could stop you from using a desktop app at a moment's notice because of a privacy policy change," noted one poster on the Slashdot Web site.