Jarred, we have created a registration system that works with .LRN (it also has an ecommerce function). It will not be included in .LRN 2.2 (we have to generalize and clean up the code a bit). It is in use at the Museum of Science and Partners Healthcare. Heidelberg Medical school is in the process of implementing this package as well.
I am happy to give you an account on our development machine if you want to test it. The code is in the OpenACS CVS.