I want to report my experience.
I have Kindle 3 3G UK: Serial no. prefix B00A with firmware v.3.3
I installed following files (Niluje):
I have also launchpad, some "kindlets" (sudoku,kindlenote,kindlegoban,snake,Kalculator), some apps (Cool reader, kpdfview).
This morning I downloaded firmware v.3.4 and installed it.
All is ok and working. The apps I listed are working correctly