Mount ext2/3 in OS X

Apparently, only NTFS file systems will automount in OS X and not at all ext2 or ext3 which is surprising given the Unix common denominator.
Nevertheless, a small package ext2fsx will apparently get over this reluctance. It can be downloaded from here.
As I had all my Music on an ext2 partition on an external drive, I installed ext2fsx on OS X. However, I still couldn't get the ext2 partition (or any of the ext3 partitions) on the usb drive to be recognised.
With that discovery, I gave up, copied the Music to a ntfs partition and used that to get it onto my Mac.
However, today when I booted into OS X, two additional volumes were on the Desktop. These turned out to be the Ubuntu / and /home that I had set up yesterday (both are ext3). Is this because of ext2fsx?
Later on I plugged in the external drive with quite a number of ext3 partitions and one ext2 partition. All of them showed up on the Desktop. This really sounds like ext2fsx is doing something but why the delayed reaction?
There is another mystery, however. On the Mac HD, I have 11 partitions in all. Eight of these are formatted to ext3. So, why are only two showing up on the desktop?