Newer phones that include large amounts (by current mobile standards) Like the Atrix (and my other phone, the Captivate) often partition them so that you don't have a huge amount of system memory that wouldn't be accessible for file storage. On the Captivate (and I am assuming it's similar with the Atrix) Samsung has a 2 GB partition for the system and the remaining 14 GB partitioned and recognized as an sd card by making its mount point /sdcard.

Therein lies the problem. The path to external storage within Android is /sdcard so apps that are installed to external storage will be there, which is the internal sd partition, not the removable sd card. On the Captivate the path to the removable sd card is /sdcard/sd_external, on my SGS2 it's /sdcard/external_sd and on my Transformer is /Removable/Microsd.

While the default location for file storage, including pictures is /sdcard, you are actually saving them to an internal sd card partition, not the removable MicroSD card.