This document summarizes new features in Movable Type 5.1, including improved support for Ajax, updated category templates, and new options for including or excluding blogs and entries. Key points include: - Ajax support has been improved for better browser compatibility. - Category templates now allow sorting categories by label in ascending or descending order. - The <mt:Entries> tag has a new attribute to include or exclude child blogs. - A new <mt:Include> tag allows embedding modules to customize output. - Text can be trimmed with an ellipsis using the new trim_to attribute.