Actually that's not correct. It looks like the 8.40.4 is the only way to go for the Mobility HD 2600 at this time, as the 8.41.7 driver does not support Mobility GPUs.
"Caution: The AMD Proprietary Linux driver version 8.41.7 is not recommended for the ATI Mobility and Integrated Products. Using this driver on any of the following products may result in stability issues. AMD recommends using the AMD Proprietary Linux software driver version 8.40.4."
Apparently a newer and more functional version of their driver will be released soon that will support the Mobility GPUs, and hopefully add missing 3D features.