I can't post in the "Qt Centre website" forum yet, so I make a small comment here and hope someone will read it.

http://www.qtcentre.org/forum/project.php?issueid=8

Tagging threads sounds like a great idea. It can improve searching and finding the right stuff,etc. But I think it could be improved by adding the possibility to att add tag about an explicit Qt class. If you have a problem with Qt::SomeClass then you can start by limiting the search to that class. That might help.

Perhaps a "quality" tag (1-5?) and a "solved problem" tag? That could filter out a lot.
Perhaps an extra "problem solved but no solution given" tag might help to sort out postings like "I have this problem ...." followed by "I solved it." which would not help anyone.

Just some ideas.