Official xournal website
It took more than a week to finally get this working. Not that it was hard, in the end, but more because I didn't know what I was doing.
There are some problems, of course. One, the refresh is inconsistent. Two, don't click the "print" menu item. I took out all the printing code because a) it seemed useless and b) it required a bunch more libraries for something that wouldn't get used. I'll look at taking out the menu item, although I might look at how "Print to PDF" works, and putting it back in there. Seems like it would be useful, if it's possible to implement.
I haven't done a lot of testing so far, just enough to confirm that it runs. You, mobileread readers, are the guinea pigs for this experiment. Let me know what sorts of issues you run into and I'll try to fix them. Also, I see that iRex has posted some more comprehensive documentation, including putting icons in the taskbar and such, so I'll look into that.
Installation: Unzip to the root folder of the device. When you disconnect from the computer you'll find two new shortcuts on the Home screen: InstallXournal and Xournal. Run InstallXournal first. It should take 30 seconds or so. Then run Xournal and enjoy.