If this project is as large as you make out then the platform for it is not really an issue. Whether you use MySQL, PostGres or SQLServer (amongst others) you will want them on their own machine and connect to them via the DBI and the relevant DBD driver (ODBC, PG etc).
I totally agree with you on that for large sites, but the system must easily support small sites as well as large. In other words, we need to have an install plan, that will work nicely on a small server, as well as for large clusters, where we offcourse as you suggest, will have dedicated database servers. Another issue for some of our smaller customers, is cost, some of the larger DBMS's can have a pretty hefty price tag. Therefor, the system should work with both a small preferably free DBMS, as well as a large commercial DBMS on a dedicated server.
As for a scripting language - why not use Perl itself? You can quickly define a set of macros and comeup with an application object that presents a partcular API. Its then trivial to check for bad code, to untaint and to run the app.
...would be pretty cool from a programmers point of view =). I did give it a few thoughts earlier, but dismissed it as beeing to hard for non programmers to learn.... aaand, I wasn't sure how to go about with the "bad code" checking... anybody have any pointers to some information about that? similar projects or something like that?
thanks for your reply! it gave some good food for further thoughts...