I'm newbie in xoops... but i think that is a very good cms: use class, use smarty templates, infinite modules types, the 2.2.x version inplement smarty support into admin section, very good cms...

But the database layer, support only Mysql... :)

My suggest is the integration of a "database abstraction" class like ADODB of John Lim or PEAR or similar, for support all database types (or the most common: oracle, postgres, mysql, msaccess, sqlserver)...

This is my little suggestion...
I hope this is usefull for the XOOPS project... :)

bye!

JakDaniel