I checked all the usual suspects and can find no reviews.
The press release is here:
http://www.dpreview.com/news/0502/05021701canon_sd400.asp
CNET digital camera reviewers march to a different drummer, we don't know when/where/what they review.
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Now that the SD400 has been released, has anyone come across any reviews of it? When will CNET be posting a review?

Chowhound
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GameFAQs
GameSpot
Giant Bomb
TechRepublic