MSN to use personal files to personalize Search?

In the quest for producing ever better Search results, the major SEs have turned to "personalization". The searcher's "profile" would influence the type of results returned, matching them with "anticipated" expectancy determined by the profile.

All very well in theory and potentially a great improvement for delivering great search results but it just leaves one tiny question... how to create such a profile in such a way that it does effectively increase the searcher's user experience?

So far, Google have "solved" the problem by letting users create their own profile (or not). That approach also bypasses any "privacy" concerns.

But MSN have floated an idea that goes a lot further. Using the index created by MSN Desktop Search when a computer user searches for files (locally) would reveal a lot about the user's preferences. This could thus be distilled into a profile, useful for generating personalized search results that have increased relevance to the individual searcher.

How effective using the MSN Desktop Search index may be in creating a discerning and effective "profile" is far from clear.

And it does all sound a bit "creepy", doesn't it... Data mining etc. I hope they will give individuals the choice at least of having a profile or not...