Alright, today was the first day back with some time on PostgreSQL. We got both 8.3.8 and 8.4.0 built and into the test environments. That is the good news. Now for the bad. The Preference Pane is really broken on Snow Leopard right now. I am going to work on that tonight and some tomorrow, and if I can get it working, it will go into the release. If not, then we get to live with the 32bit version of the Preference Pane for a few weeks.
One of the big changes in this coming release is actually a long requested one. The ability to maintain multiple versions side by side (only one running at a time). STarting with this release the current version will install into /Library/PostgreSQL8/versions/current_version_number/* the bin, lib, share and other directories will be symlinked to the current version. Included in the distribution will be a shell script pg_set_version.sh that will allow you to select any installed version and change it if PostgreSQL is not running. This also means that we will NOT be upgrading your current data directory. You have to do that yourself (for the moment).
So how will you change it? easy, open Terminal.app and type sudo /Library/PostgreSQL8/pg_set_version.sh 8.4.0 to revert to your 8.4.0 installation. Eventually this will also be part of the preference pane.
So with all of that said, look for the new builds to hit the server sometime after October 1.