Ported Greasemonkey to Fennec – aka Firefox Mobile – Took the compiler version and had to change just a few small things. (no app-content container).
Some simple screenshots
Before Greasemonky on Fennec
Enable the Fennec Extension
Greasemonkey going to work on Google.com
This won’t be my Firefox Mobile Challenge entry 
but a step towards something – if any idea sparks. I really love that Nokia N900!
Next up… getting FireVortex to work… (runs on Greasemonkey)