SiteMesh 2.4.2 is a very stable and well, it just works. As such, focus has been shifted to the development of SiteMesh 3.
The SiteMesh Change Log Dashboard shows a top level view current and previous versions.
You can also view the changes for specific versions:
Version 2.5 - Issue tracking for version 2.5 exists in two locations. The original JIRA server and the new GitHub server.
Verrsion 3.0 - Issue tracking for SiteMesh 3.0 exists in two locations. The original JIRA server the new GitHub server.