Yesterday's announcement was more a press release than anything else,
since ACS 4 Java has been around for some time.
As has been said here before, the OpenACS project is an "umbrella"
project. Initially we are modifying ACS 4 Tcl to become
database-independent, and porting the data model to PostgreSQL. Then
going on to improve current packages (such as the Content Management
System) and add new packages/functionality.
As soon as this is done, it will be much much easier to port ACS 4
Java to other databases, like Postgres. I am guessing that people will
jump on ACS Java and do that, and our community will be glad to help.