Even though I would have liked to release 0.5.1, there was a serious bug in 0.5.1-RC1 that meant it didn't get the testing it needed to make this 0.5.1. We hope to release 0.5.1 pretty soon though. For more information about this release, see the forum topic.

Less than a month after the final release of 0.5.0 the list of bug in 0.5.0 was so big that we have started the release cycle for the 0.5.1 bugfix release.

In this release you can find a few new small features like an extra news group for opening and closing industries so you can disable all those industry production changes and still get notified when industries are created or shut down.
The most noticable fix for people who like to play with the AI is that AI processor consumption has been greatly reduced, although at the price of some intelligence. Furthermore some crashes and a desync have been fixed.

As the installation of the Microsft Unicode layer for Windows 95, Windows 98 and Windows ME proved to be difficult for people (yes, reading is difficult), there is now a special win9x build for those platforms. Users of Windows 2000, XP, 2003 and Vista should continue to use the win32 binary.

Take a look at the forum post for more information about this release.

You might remember that back in December we talked about Windows 95/98 and Windows ME and why their support for the nightlies has been discontinued.
The good news is that the problem has been solved, provided that you download the win9x binary. All users of more recent Windows OS's (2000, XP and Vista) should get win32 to enjoy full UNICODE support.
What is the bad news you say? None :)

On behalf of the OpenTTD team I am proud to present you OpenTTD 0.5.0 (the final version this time). Those who have been us since the release candidates, we thank you for your diligent testing and bugreporting. For the users who are only now venturing to upgrade from 0.4.8, you will see a *LOT* of changes, all for the better. The various RC's have already talked about this, but let me restate the biggest changes since 0.4.8:

We have a new fast, robust and flexible pathfinder, electrified rails support, a brand new terrain generator, full UNICODE support and better multiplayer. NewGRF compatbility (modding) has been greatly enhanced with support for changing stations, adding sounds, more vehicle sets, etc.
The smaller feature- and buglist goes on and on, but we'll let the user explore this. All users of 0.4.8 are encouraged to update to this new release.

Please read the full announcement at the forums as it contains important information for Win9x/WinME and international users.

Instead of the final 0.5.0, we have released yet another Release Candidate, #5 to be precise.

Release highlights of this RC are various fixes for 'cheats' with flooding, Korean, Simplified Chinese and Traditional Chinese translations. For a full list, have a look at the tt-forums post here.