Movable Type 2.51 released. You can view the Changelog or just go straight to the Download Page.
Along with some bug fixes and few tiny new features, there is one improvement that really makes this release worth the download. During the rebuild process, MovableType will now check to see if the data in the file has actually been updated. If it has, it will replace the file as usual. If it hasn’t, it won’t replace the file, but instead, leave it exactly as it was. This doesn’t save any rebuild time (well… a few microseconds… maybe) but that isn’t the point. The advantage of this is that, if the page hasn’t been updated, your web-server will continue to inform properly contructed clients (web browsers, and RSS readers, alike) that the page hasn’t changed and that there is no need to download the entire thing again.
Thanks again, Ben and Mena.