Almost all of the changes are cross-platform, no osx-specific changes. Since you asked, here is a summary of changes since r947:
- speedup of tga and pcx external images
- further slight speedup for lightmap loading
- change sv_aim default value to 1 (i.e. turn off autoaim)
- add 'prev' and 'next' keywords to the 'cd' command
- work around a linux cdrom issue (playback might not start for a while after a stop).
You can follow the development history from
http://sf.net/p/quakespasm/code/