Andrew,
Just to let you know what side I'm on I don't think I would run an Apache based OpenACS. I've got no legacy code and I think Apache 2.0/mod_tcl has maybe 80% of the features of AOLServer 4.0, plus AOLServer has 10 years in the field. I do think Apache has better support for virtual hosting which is one reason why Apache/PHP is so popular.
I know there are big differences between Postgres and Mysql. From a business standpoint Postgres is easier to distribute.
In some ways I see this like AOLServer on Windows, I would not use it for production but it's nice that it's there. I do think that OpenACS would get much more exposure if it ran under Apache and could perhaps become an Apache project, but there are very large hurdles to getting there. I do agree there is no technical reason to even try.
