Wow! What happens if you post a proper message? Swedish academy will be calling to get you some recognition nobility? :-) Thanks for the many detailed and exact links!

I need to get myself equipment and skill to do this. I read the stuff and watched the video to see if it is achievable. Backing up (not to the endevaour but simply the data) will be my first step.

Equipment
Phillips #00 Screwdriver
TORX+ size 6 (for the keypad removal)

optional
Gloves
Universal Opening Tool Set - Nokia SRT-6 (in videos screwdriver is used as opening tool)
Opening Tool - Nokia SS-93

Process Descriptions

Videos
http://www.youtube.com/watch?v=aVEHm325-z8 "Nokia N900 Disassembly"
http://www.youtube.com/watch?v=pDQ81cahD1c "Repair / Replacing Nokia N900 Display Screen LCD"

Manual
Picture-Step-by-Step-Guide in the N900 Service Manual - Level 1&2 (see
http://wiki.maemo.org/N900_Hardware_Hacking#Resources)

Screen removal: Steps 1 to 8
Keymat replacement: Steps 1 to 13

Buying List
Phillips #00 Screwdriver
TORX+ size 6
N900 screen
N900 keypad (preferably German qwertz)
(optional NOKIA N900 - A Cover Assy)
(optional M1.4x2.8 screws)

Search terms (e.g., for ebay)
N900 keymat "OEM Nokia N900 Big Keypad" or "qwerty N900 keymat" (could not find a German keymat"
N900 screen "Nokia N900 LCD Screen Display" or "New Touch Screen Digitizer + Frame"
N900 screen cover "NOKIA N900 - A Cover Assy ( Front Cover ) - Part #0253126"