A Wiccan student in Ohio succeeded in getting his school to follow a ruling  passed 17 years ago about prayer at graduation.
http://www.nbc4i.com/cmh/news/local/article/school_district_cancels_graduation_prayer/15707/

A really good follow-up here:

http://blog.au.org/2009/05/14/justice-in-chillicothe-school-officials-cancel-clergy-prayers-at-graduation/