ext2fsx -- I need to know more about this.

I had install ext2fsx yesterday, and as I already mentioned, the two Ubuntu partitions now show up after startup on the OS X Desktop.
Strangely, however, the other six ext3 formatted partitions do NOT show up here. I wonder why.
Also, it seems that these partitions are mounted read-only as I cannot add anything to them from OS X.
Here is a thread that mentions how to get write ability in volumes mounted by means of ext2fsx although I haven't yet tried this.
Some more useful threads (1 and 2) on the ext2fsx in general. But, in reality there seems to be very little at all written about what looks to me to be potentially a very useful tool. Why is this? One reason could be that it just doesn't work very well and nobody is developing it right now.
I posted two threads on this myself today (MacRumors and Ubuntuforums) but up to now haven't received any replies.