MSN Search testing personalization?

Different search results for users with cookies turned off...

[AdriaK]

If you go to MSN Search with your cookies turned off, you get different results than if you have cookies enabled.

We discovered this because we noticed that different people in our office were consistently getting different search results for the same query. We think this may mean that MSN Search is personalizing results based on your cookie.

Is anyone else seeing this behavior? Does anyone have another explanation for why this is happening?

[ByronM]

Most likely because MSN inbeds Overture listings in results and if you disable cookies they probably don't embed these results because they couldn't reliably track them.

[AdriaK]

Hmmm. No, that's not it. The Overture results appear whether you have cookies turned on or not.

(And btw, I wouldn't exactly say that MSN Search "embeds" Overture results in their search results. Overture results appear in a separate section called "Sponsored Sites." They're clearly labeled.)

Any other thoughts?

I'm suprised that no one else has noticed this, because if you use WPG, for example, it screws up your results for MSN--you'll get different search results for WPG than if you (or your client) actually run the query on the site.