I had waited far too long and needed a way of downloading photo's attached within GMail. This is one missing feature of GMail. Download All Files App allows you to download attachments within GMail or WWW etc. When you hit Preview within GMail you are presented with a pop up choice to download. From here you can browse to the location i.e. external micro SD and a folder of your choice/ folder you created. You can rename the downloaded file if you wish. It works very well and ensures my internal memory is reserved for more useful things!
Here is a link explaining:
http://maketecheasier.com/save-attachme ... 2011/02/19
Thanks