The text of this post is taken from the announcement made by Wilma Hodges – The Sakai Community Facilitator.
I’m pleased to announce on behalf of the worldwide community that Sakai 12.1 is released and available for downloading! 
Sakai 12.1 has 97 improvements  in place including
- 20 fixes in Gradebook (aka GradebookNG)
- 9 fixes in Tests & Quizzes (Samigo)
- 7 fixes in Assignments
- 6 fixes in Resources
- 5 fixes in Lessons
Other areas improved include:
- Section Info
- Site Info
- Web Content
Four security issues fixed in 12.1 (details will be sent to the Sakai Security Announcements list)
Please also note the upgrade information page  for important notes related to performing the upgrade. 2 Quartz jobs need to be run to complete the conversion steps for Sakai 12, including a new one for the Job Scheduler in 12.1.
 Downloading information available at – http://source.sakaiproject.org/release/12.1/
 12.1 Fixes by Tool – https://confluence.sakaiproject.org/display/DOC/12.1+Fixes+by+Tool