Oh yes, there is one similar topic but its made at 07-01-2008 so we can claim this as an update to it, how things are now.
I have been workin on this guide for a while now and its not 100% ready yet. I still need to add more videos about dueling different classes. Got like 5 videos at the moment.
Here: wLock PvP by Zafer - Outland (A)
Please read the introduction before takin a look at the guide.
Most important there is the part about the sitemap. The guide is messy without it cause I made it in base of a blog.
I suggest you to start reading with articles:
# Your talent spec.
# Gear.
# Primary profession(s) to use.
# Socketing your gear.
# Addons
# Basics about pvping as a warlock
# Macros
# Keybinding
And after that moving to watch the videos
Please comment if there is things I should add in the guide^^
EDIT
09.05.2010
Video added
Vs. destro and affli locks
EDIT
25.05.2010
Video added
vs. retribution paladin
EDIT
30.07.2010
Video added
Vs. Elemental Shaman
EDIT
09.09.2010
Video Added
Vs. Feral druid