I take a quick look at Gparted, I find there is a format menu, so seems this tool support format, also I find in Suse 10, there is a tool named partitionar, which also have functionality to format, seems we can use them to format...(I have not look into them at them moment).
Gparted uses libparted underneath. Because formatting is a small subset of Gparted features perhaps it is better to use libparted to format the device directly, in this case? John