Most important thing this time is the experimental support for connecting to PostgreSQL servers.
Get it from the download page.

Also noticable:
* Completely rewritten interface to plink.exe for SSH tunnel connections. Now supports dialogs which ask for trusting unknown host keys.
* Bind parameters in SQL queries. When your SQL query contains one or more ":myparam:" occurences, the right hand box offers to set a value for these parameters. Adrien, a former contributor from France, has developed this new feature.
* The "Find text on server" dialog now also works on MSSQL and PostgreSQL tables.
* The table editor now supports partitions, in a new read-only tab. That way, partitions a) can be seen by the user and b) get included in the CREATE TABLE code tab.
* Filter in data grid column selection
* Disable SQL hints on result tabs: Some users complained about the potentially huge tooltips on the tabs of a SQL query result. These quickly hide important parts of the result rows. If you're one of those annoyed users, you can now disable these tooltips with a new checkbox option in Tools > Preferences > Data appearance > "Popup SQL text over result tabs".
* Database selector: In a session configuration, you can restrict the databases to display. That was just a normal drop down menu previously. Now, you can check databases and uncheck them in a pulldown menu. Also, the connection used to get the names of all databases is recycled for each click, so only the first pull down click establishes a new (potentially slow) connection.
* The installer for HeidiSQL now uses localized messages in 23 different languages. Language is auto-selected by checking your Windows locale.
* The user manager now supports granting privileges for VIEWs. This was not allowed until now, because I misunderstood the MySQL documentation here. See the forum thread with alfiqmiq for details.
* Ask user to confirm unsafe UPDATEs/DELETEs in query tab before executing.
* Switch character set from utf8 to the fixed one called utf8mb4 in MySQL.
* Turn readme.txt into a more comprehensive online help document
... and even more:
* Support semicolons in MS SQL passwords
* Clone hostname for a cloned user
* Ask to close HeidiSQL processes while installing
* Check if all indexes have at least one column when creating or altering table to prevent creation of empty index
* Support primary keys with KEY_BLOCK_SIZE=xyz
* Allow disabling the creation of start menu icons in the installer
* Auto-uppercase data types of routine parameters
* Display filename with path in query tab hint
* Support changing active result tab per shortcut, Alt+Left and Alt+Right.
* Disable UNSIGNED and ZEROFILL checkboxes for BIT type columns
* Fix missing table alias on MSSQL2K
* Support query timeout on MSSQL and PostgreSQL. Make customizable per up/down scroller in "Advanced" tab of session manager.
* Add "Save as textfile" action, and include that in routine editor > "CREATE code" tab > context menu.
* Activate "Select all" action when it appears in a valid popup menu.
* Increase maximum port number from 2^16-1 (65535) to 2^31-1 (2147483647).
* Add a 32bit-only installer, for users who want the 32bit version on a 64bit Windows.
* Support searching for unformatted integers and floats in filter panel.
* Fix truncation of MSSQL routine body to 4000 characters, as a limitation of nvarchar(4000).
* Fix SynEdit's double minus comment bug
* Use prettier "Consolas" as default font for TSynMemo editors, when available, as an alternative to the old-stylish "Courier New".
* Fix SQL error when using "Quick filter" > "More values" in MSSQL and PostgreSQL.
* MSSQL: Return date/time string value as expected by server.
* Enable foreign keys editor on NDB cluster >= 7.3.x.
* Add support for geometry data types in PostgreSQL.
* Support renaming tables and views on PostgreSQL.
* Fix EStackOverflow in TSynHashEntry.AddEntry when adding too many table names.
* Include SQL_TABLE_VALUED_FUNCTION's in MSSQL object browsing
* Support DEFAULT clause in PostgreSQL table structure
* Keep compatibility with older MySQL servers when getting a trigger's CREATE CODE
* MSSQL: Return float values as expected by server.
* Introduce handling of stored functions in PostgreSQL: Displays functions in database browser, enables function editor and "run routine" button with argument handling.
* Add support for MSSQL datetime2 column type.
* Allow applying CURRENT_TIMESTAMP to DATETIME columns.
* Add "check/uncheck all" button to column selector in textfile import dialog.
* Add 64px, 128px and 256px versions to main icon.
... and for the nerds: the entire changelog