It is a bug fix release. No new features, NO security fix.
The following issues were fixed in this release.
106033 IE9 RC: Unable to move category/folder on Manage Categories/Folders screen
106034 IE9 RC: Unable to move widgets on Manage Entries/Pages screen
107561 Template load error occurs when a plugin calls MT::Template::load_file with an invalid file path
107157 key and index modifier of MTGetVar tag do not work in dynamic publishing
105414 Always output by ‘png’ when make thumbnail file on dynamic
107692 Got an error when doing validation in “Manage Folders” and “Manage Categories”
86133 Error when saving a template on Template Preview screen
106214 encode_xml does not remove invalid characters in XML
106215 mt:Include is not cached in “memcached” environment
106217 mt:Include that has “key” attribute gets an error in dynamic publishing.
106219 Include that has “key” attribute cannot be used in statically and dynamically at same time.
106258 mt-search.cgi fails with IncludeBlogs=all after upgrade to MT-5.1
106128 MTIfMoreResults can’t work in dynamic publishing.
106159 mt:MultiBlog that has no arguments overrides “local_blog_id” in dynamic publishing.
106202 [Patch] General Settings doesn’t display “Attribution-NonCommercial-NoDerivs” license name
106305 MT5.1 Search code regressions
100361 URL on Registration Notification is relative path.
106491 Search and Replace Limited to 126 entries
107390 Theme elements order required.
107443 Memory Leak: Reblessed objects contain cyclic ref
106651 “Request-URI Too Large” error occurs when restoring a backup file which contains a lot of assets
107105 Thumbnail for file-type asset is not displayed on the search results screen for asset
107125 MTInclude tag does not work with key modifier
107341 Duplicated cache filename when using PHP SSI
106513 MTArchiveList archive_type=”Category-Daily” doesn’t work under static publishing
106532 Browsing Select a Blog Style screen generate styles.css template
106535 Checkbox custom fields are not saved properly on Edit Entry screen in some situations
83208 MTIf doesn’t work with a hash variable under dynamic publishing
105747 Custom fields’ data can be imported by entry import even if there are no custom fields in the blog
106356 “Create Blog + Website Administrator” permission user cannot clone blog
106358 FF5: can not go back to WYSIWYG mode after switching to HTML mode
106359 Chrome: Malfunction when switching mode from HTML to WYSIWYG
106378 IE9: Malfunction of text decoration in WYSIWYG mode
106380 IE9: Can not insert item and image when WYSIWYG mode
106395 IE8: When setting anchor link at web page edit on IE, [editor-content.html] is added unintentionally
106435 Original relative URL is not preserved when we click the Link button.
104044 no author ID record in mt_category when the blog are created by custom theme
107682 Comment author disappears from the commenter list when he is unbanned
107663 Cannot eject value in hash, while dynamic publishing
107664 [Customfields] If you change the basename, data you entered will disappear
105360 Doesn’t display entries correctly when include_subcategories=”1″ and include_blogs=”all” are configured.
106786 Can’t remove multiple filters at once
106916 Styling : the display breaks when the category name is long
106925 Unable to cancel deleting a comment properly on Edit Comment screen
69877 MTCalendar month=”this” doesn’t work on published entry archive
107587 Editor cannot add tags at System > Manage Assets
107601 Community Blog’s ‘Powered by’ widget does not show ‘Powered by MT’ icon
107818 Cannot move to login screen after created a new blog with French
Update my blogs as usual.