[Ozric]

Oh yeah, in light of the current issue involving the display of covers on the Nook Color, I'm sure now isn't the best time to mess with it. Mainly I was just wondering if there was an optional Preference somewhere that would prevent Calibre from copying the thumbnails to the device.

Ideally, the Gallery app will get an update that allows for folder browsing or some sort of filtering.

EDIT:
For what it's worth, I've discovered it's a simple matter to do a *.jpg search on my device's Book folder and delete everything it finds to purge all the thumbnails. I don't know if it's really indicative of anything, but I didn't notice any changes in cover thumbnails when browsing books--books that were displaying covers before the purge still display them, and books that were not still don't display them.

Hopefully B&N straightens out this issue soon.