Actually, I think that if things here are reorged then it needs to be done a lot differently than what's proposed

Use the tags, not specific categories.
Group the tags categories in the same manner that the current categories are kept.
Subject befitting multiple categories will appear in that area.
Make it a requirement that the major tag-category group is identified when a user creates a thread (there should be very few of these); or the requirement that there needs to be one major tag-category

For example:
Topic: Gimme New Games for my N800
Tags: N800*, games, puzzles

* is the primary tag category since its the first one there; will appear under the N800 area on a portal-like page

Reorg solved; search improved; usablity increased