/mnt/removable is where I go in a terminal session.
[don@localhost ~]$ cd /mnt/removable
[don@localhost removable]$ ls
Mike/ Next Blu Builds/ slavedrive/
My Pictures/ Recycled/ System Volume Information/
This is listed as sda1 in my desktop devices icon as well.
Edit: Depending on what you plug in it may change, here is what happens when I plug a second mass storage device in:
[don@localhost removable]$ cd /mnt
[don@localhost mnt]$ ls
cdrom/ cdrom2/ floppy/ ipod/ removable/ removable1/ slaveWD200/ winXP/
So, go to /mnt to see what the mount point will actually be called, then you know how to mount it.