Before Honeycomb 3.2, apps only had to request for the permission WRITE_EXTERNAL_STORAGE and they would have write access to both the internal and external so-called "sdcard" sets of memory. Now, apps have to request for WRITE_MEDIA_STORAGE if they want to write to the external SD card, but many of them have not yet been updated to do so yet. This affects file managers / explorer / compression utility type apps most often because users would tend to use them to copy / move / zip files within the file system.