I've got two of these puppies, and have been hanging on to them far too long. I got them for free, but I've never so much as powered up a machine with them installed to see if they work or not. From what I understand there are very few real live applications that can actually make use of more than two serial ports at a time, so these things may be worthless. But they're still kinda cool.
I heard of one guy who was using one in a machine with some X-10 home automation gear, but very little detail on how he made use of it.
If you're interested in paying whatever it might cost to ship them to you from 57105, drop me a PM.