for backwards compatibility with software installers, the 16/32 GB internal drive is mounted as /sdcard, so in a way, yes.
The external cards, either microSD or full sized SD in the keyboard are mounted under /Removable which is not known to android installers.
However, underneath, it looks like:
/mnt/sdcard (default place for android sdcard installs)
/data/Removable/MicroSD
Most apps will look in both locations for music or video files. But I don't know of a way for apps to put data under /data/Removable