(Image from http://bees.tennessee.edu/diseasepest.htm)
Jennifer reported that she does not treat for nosema at the lab or with her own colonies at this time. She does check for spores periodically and has yet to see any. She mentioned that many people have been using Honey B Healthy (which is available through many bee supply companies like Brushy Mountain). She suggested just being aware of what you have in your hives can help. This can be done at home if you have a compound microscope and preparing the slides. Since we are located in Tennessee, she suggested John Skinner from UT as an excellent resource.
We very much trust Jennifer's advice. Greg has mentioned that if there is a Holy Grail of beekeeping, she knows where it is. We hope you and your bees benefit from this information.
If you would like more information, check out this document about diagnosing and treating nosema from UC Davis. The more information you get on this topic, the more informed your treatment decisions will be.