Get it here.
This beta has a few fixes over b4, but it's primary goal is Leopard fixes. I'm still investigating a problem with word counts on Leopard. I've had a few reports of incorrect word counts, but I haven't been able to reproduce it myself. It's mystifying so far but I hope to get a fix in time for 4.1.3 if it is a problem with MacJournal and not just system configuration. Leopard users, please let me know of any problems with this build.