Tomasz Motylewski has set up a mailing list dedicated to the discussion of this driver (and how to make things talk to it). Subscribe by sending a message with the BODY "subscribe linux-arcnet YOUR REAL NAME" to <firstname.lastname@example.org>. Then, to submit messages to the list, mail to <email@example.com>.
There are archives of the mailing list at: http://tichy.ch.uj.edu.pl/lists/linux-arcnet/
The people on <firstname.lastname@example.org> have also been known to be very helpful, especially when we're talking about pre-release Linux kernels that may or may not work right in the first place.
Finally, there's another mailing list, <email@example.com>, which is for general discussion of ARCnet-related topics. Lots of people using ARCnet in industry read that list.
There's a file called ChangeLog in the Linux-ARCnet distribution package. It lists all the changes made to the driver, version by version, since the beginning of time. It's useful if you want to know what I've been up to all this time.