Windows 7 changed the folders in c:/users/$USERNAME around a bit.
My Documents is now just a link to the new folder Documents Application Data is now just a link to the new folder AppData/Roaming Local Settings is now just a link to the new folder AppData/Local
How is this going to affect Wine? Well-behaved apps that use CSIDL_PERSONAL to get at "My Documents" or "Documents" will work regardless, but users or badly behaved apps might start expecting the shorter directory names sometime. (I always hated the spaces, anyway.)