I wouldn't hold my breath on this, though. We still don't see transparency for PSDs, for instance, and with so many performance issues that are still outstanding, my guess is they'll rate this request rather low. But it's better to put it on their list than try to figure out what they'll slot in to our releases when.
You can't check white backgrounds (255,255,255) accurately in Bridge anyway. I have a Photoshop action that adds a Levels adjustment layer, moves the black slider all the way to the right (253), and duplicates that adjustment layer. If there are ANY non-white pixels, you'll find them immediately.
This request has been addressed.
With the latest version of Bridge, you will be able to "Hide Tiles" and control the background color of the thumbnails from pure white to pure black.
Although the Bridge v10.0 is not yet released, you can download the latest Bridge version from our prerelease website: https://www.adobeprerelease.com/ Select Adobe Bridge. Download v10.0 Drop 4 (or latest) from there.
In this version, at the bottom of the Content panel, you will see a check box to hide the tiles. After you hide the tiles, you can go to Edit menu->preferences->interface and use the "Image backdrop" slider to change it to pure white (or pure black or anything in between).
This works with transparent thumbnails as well (as a backdrop to the transparent areas)
Senior Product Manager, Adobe