Extending MIDP on the 6600 
Here's an interesting idea:
Since Symbian is a multitasking OS you can run multiple application in parallel. Why not write a native symbian application that autostarts when the phone is powered on and listens on a tcp socket.
When a midlet want's to read or write files, get the IMEI or whatever isn't yet possible it connects to the local server and asks the native application to do so.
Okay the native app should only accept connections from the localhost and maybe should ask the user if it's okay to write that file or read this file or whatever it's asked for. (Similar to what the MIDP runtime does when an unsigned midlets asks for network connectivity and similar security related things.)
I'm pretty sure this can be done but unfortuneatly I'm not a Symbian C++ guy to write up the native stuff. So if anyone want's to write such an application: Go ahead.