There have been a lot of questions about 1.24 and DotA, so I'm going to take the time here to answer them.
A new warcraft patch has been released with the focus on fixing a bug that could cause you to get a virus when joining a game. As a result of this, some core Warcraft 3 functions that are used in DotA and most other maps had to be removed. To make up for the significant loss in functionality, new replacement functions were also added to the patch.
Some confusion comes from the fact that some maps like 6.59d work under 1.24. This is only partially true. There is nothing special about those maps, 1.24 is configured to run some maps in temporary 1.23 compatibility mode while 1.24 is further developed. The patch has not been properly configured to run 6.61b in this mode, so 6.61c will be released. That map has no changes except the version string.
As a result of the function changes, maps are not cross compatible between 1.24 and pre-1.24. A lot of code in has to be rewritten for maps to become compatible with 1.24. The next version of DotA (6.62) has all of its code updated to follow the 1.24 requirements.
As of right now, 1.24 still has various bugs in it's functions that prevent most 1.24 maps from running properly on it. As these issues get fixed in coming 1.24b/1.24c patches, 6.62 beta will be updated alongside them. As soon as the new patch is stable and 6.62 is tested on it sufficiently, it will be released. Hopefully the map will return to a stable code state in the very near future.
Once the 6.62/1.24 situation is over, regular map development will resume. The versions that follow it will most likely focus primarily on balance improvements and performance tweaks.
For people that cannot easily do multiple patch upgrades (net cafes for example), I recommend you wait until 1.24b is released before undergoing that effort.
If something isn't clear, feel free to PM me and I'll try to answer it.
Earlier post about this topic.