Resources for understanding SQL Server locking and concurrency? As demonstrated by a recent question of mine locking and concurrency are HARD.

Can you suggest any good resources for intermediate-to-advanced SQL professionals to do a thorough study on these that would, properly learned, enable better navigation of all the inherent pitfalls in this area?

I'm thinking of all kinds of resources--tutorials, blogs, manual pages, PASS sessions, or anything.
Best book on the subject, and the most complete resource, is Kalen Delaney's SQL Server 2008 Internals. You really can't do any better. Another good book on the subject is Chris Bolton's SQL Server 2008 Internals and Troubleshooting. I don't think it's as complete as Kalen's book, but it does cover things pretty well, especially around locking and concurrency.