Kaoryia's gVim builds for Win32/64 come with a number of extra, non-official patches enabled.
Some of them are pretty clear:
:set charspace=-1, for example, will tighten the space between characters;
:set transparency=250 will do what its name implies.
But there is also this patch: async job, by Taro MURAOKA, briefly described in the source as:
job.c - Asynchronous job support
Does anyone know what exactly it does, with perhaps an example about its usage?