Is a PHP module planned ?
Possibly, that depends on if a module already exists that can be intergrated
This idea will really make this much more useful.
PHP5 is available as CGI, and has SQLite embedded. There are PPC sources http://www.entropy.ch/software/macosx/php/
The Wii can then be used for a wide range of things, from hosting your blog, creating a BT tracker, XMPP Intant messaging, forums, having a test server... to running a ERP web application at your office LAN.