I found a nice piece of software for the Nokia e61 (and other Symbian S60 3rd phones aswell). It is called e32frodo or Frodo S60 and you already guessed it - it is a C=64 emulator based on the Frodo sources:

Frodo is an Open Source Commodore 64 emulator for many platforms. I have making Frodo Symbian ports since the year 2001, and all older Frodos are free. For the newest S60 3rd edition phones, the Frodo is also free (also source codes are available), but without audio.

I donated a little fee (you can define how much on your own) and got a full version of the software instantly - a few months later I even got a software update by mail - very convenient.

Here is a little video of the software in action: e32frodo_in_action.mp4