When importing from a camera connected to USB (at least for a Canon EOS 40D Firmware 1.1.1 in my case), lightroom generates wrong folder names when organizing folders by date, at least for the "2011/2011-07-22" format (I guess it's the same for the other formats).
I use Lightroom 3.4.1 on Windows XP 32 Bit SP 3 and my time zone is CET+DST (Paris, Berlin). I shot six photos an hour apart around midnight CET+DST from 21:30 on Thursday to 02:30 on friday (I changed the camera's time for that) and got the following folder/file structure using a USB connection to the camera:
Clearly, the two marked files are in the wrong folder. Note that the file naming itself (date and time) is absolutely correct!
When I import the same six photos using a card reader from the CF card, I get the correct structure:
2011\2011-07-21\20110721-213022-IMG_0314.CR2 2011\2011-07-21\20110721-223033-IMG_0315.CR2 <<< now correct folder 2011\2011-07-21\20110721-233041-IMG_0316.CR2 <<< now correct folder 2011\2011-07-22\20110722-003049-IMG_0317.CR2 2011\2011-07-22\20110722-013055-IMG_0318.CR2 2011\2011-07-22\20110722-023102-IMG_0319.CR2
This seems to be some "time zone / daylight savings time bug" affecting all photos made from two hours before midnight until just before midnight (my local time is UTC plus two hours) - but why only for camera USB and not for card reader? I didn't test it for a date that has no DST, but I would bet that it would affect photos from *one* hour before midnight, then.
P.S. The wrong folder structure also already shows in the folder preview in the import dialog. Here is the wrong structure using USB to camera: