Wilbur 1.89 is out at http://www.fracterra.com/software.html for interested parties. It has:

* improved techniques for status updates, giving improved performance in many cases.
* multithreaded precipiton erosion to go a bit faster sometimes.
* flow finding should be more correct at the cost of being a bit slower.
* no 32-bit version because I'm tired of checking if that code even runs.