harmonyst.org

The School of Public Health is using Moodle for its online courses, and they are turning out very well. However, Moodle is a course management system, and has not been developed as a student information system. There is apparently an add-on module for Moodle in development, called Online Education Portal, but it is not yet clear how robust an SIS this will turn out to be.

While Blackboard and WebCT have received a significant open source challenge from the likes of Moodle et al., open source student/school information systems are not nearly as well developed. Centre SIS was perhaps the most widely used and highly developed, and it seems that a fork called Focus/SIS is picking up where thay are leaving off. Both are PHP/postgresql systems, which is both an advantage in that postgres is a bit more sophisticated and powerful than mysql, but also a disdvantage in that the majority of other learning paltforms (like Moodle) use MySQL.
There are currently people trying to integrate Centre and Focus with Moodle, but the progress is not yet significant. The IMS enterprise standard is the key as usual, but the integration is not o.t.b. yet.

I am also looking at Uni Open, a student and university management system out of FernUniversitaet in Hagen, Germany. I have very high hopes for SchoolTool, a python/zope application which looks like it will be ready for production implementations next year. The demo looks really slick. SchoolTool would be an ideal solution for educational institutions also employing plone/zope for learning centers and content management.