Window memory is voodoo. The rules have changed again, and my carefully laid out window to show the order of installing everything gets alphabetized and meaningless.
New QGIS 2.8.3 installer with the installer packages themselves numbered for install order.
This is also the beginning of a system minimum update. GEOS and PostGIS now have a minimum system of Mt Lion (10.8), though Mt Lion appears to be now dead from the absence of a recent security update. I need to support Mt Lion for a short time at least, but I recommend at least Mavericks and in the near future I might shift the minimum to Mavericks.
I've made the installation of QGIS simpler, by including the GDAL and Matplotlib packages. For now this only applies to the long term support release (2.8), and I'll probably only update the download when QGIS is updated, so the separate frameworks may be newer than what is packaged with QGIS. If I try to update the whole thing every time one part changes, it'll just get messy. I also added a note to the first readme about installing multiple versions of QGIS, basically don't.
One thing I found right away is the Yosemite upgrade killed my installed Postgres. I think Apple's upgrade process did a search for certain postgres folders (for temporary files, no data files are deleted) and deleted them, probably assuming they were for their Postgres and that they would be reconstructed later in the upgrade process. I added some repair instructions on my Postgres page.