Tiled 0.5.0 marks the biggest update since 0.3.0, but unfortunately it's not as big as we had wanted it to be. Object support didn't make it in and the new tile image handling still leaves things to be desired. However, a lot of improvements have been made in other areas like for example much more options for the brush, masked tileset support, cursor highlighting and a whole bunch of fixes. Here comes the full list:

• Added width and height attributes to layer element
• Added layer properties, analoguous to tile and map properties
• Added a version attribute to the map tag
• Added a basedir attribute to the tileset tag (suggested by Radomir Dopieralski)
• Added support for shared images (merged in Rainer Deyke's shared images code)
• Added support for masked tileset images
• Added support for highlighting tile under cursor
• Added support for creating an image snapshot of the map
• Added additional zoom levels (by Marc Ilgen)
• Added background color option (by Marc Ilgen)
• Added option to show coordinates on each tile (suggested by Ahmed Mohombe)
• Added an option whether to automatically create tiles from tileset images upon import or not.
• Added support for reading TMX/TSX files from URLs
• Added the RandomBrush for doing 'spray-paint' painting (suggested by Rainer Deyke)
• Added the brush dialog, and support for a wide range of brush operations (Nephilim, Rainer Deyke, et al.)
• Added a message framework for reporting load/save problems to the user
• Improved GUI in several places
• Improved TMX loading, it is now much more forgiving
• Optimized rendering of isometric maps
• Completed the Search/Replace dialog
• Changed the MultisetListRenderer to show tiles actual-size when selected
• Generalized the dialogs for properties and added delete capabilities.
• Fixed determining the relative path to tileset images
• Fixed some old things in the DTD (suggested by Radomir Dopieralski)
• Fixed drawing artifacts in selections
• Fixed Copy, Cut, and Paste menu options to be disabled when no map is loaded
• Fixed cancelling Save As operation still saving the map
• Fixed inverting selections