I figure I'll weigh in on the issue as well.

The modules and such that I've been writing in XOOPS were in a couple of instances found in the Joomla! and Drupal communities, but I found the features to be lacking enough that I decided to just write my own module. (Which has also served as a neat way to learn how to write modules.)

I agree with Trabis that the work to do an effective port can be just as much or more than writing a new module from the ground up.

In the case of Joomla!, a lot of their newer modules use the MVC object model, and when compared to XOOPS, that's like trying to stuff a square peg in a round hole.