I've started a project to create a centralized hub for UT3 editing tutorials. It will take the form of a book index, so it will be laid out in a way that should help beginners become experts simply by following down the list. I will not be writing (any?) tutorials myself: the page will simply be a list of links to any tutorials others have written. I did the same project for UT2004, and many of the links were to UDN or UnrealWiki, but there were also a lot of links to mappers' own websites.
For more information, visit my Tutorials Home, UT3 Tutorials Page (incomplete), or this thread at BeyondUnreal.
I will not follow this thread, so any links or help you want to contribute should be emailed to me or posted in the BeyondUnreal thread.