Today we have released our first release candidate for 1.0.0. This means that it is unlikely that any more features will be added to 1.0.0. More information about this release can be found on the forum.
Today we updated openttd-useful.zip to add an extra library. If you want to compile upcoming releases/nightlies/trunk you have to update.
If you do not compile OpenTTD yourself or you are not using Microsoft's compiler you will not be affected.