Grand Central Dispatch and Blocks Links.

http://cocoasamurai.blogspot.com/2009/09/making-nsoperation-look-like-gcd.html
http://cocoasamurai.blogspot.com/2009/09/guide-to-blocks-grand-central-dispatch.html
http://www.friday.com/bbum/2009/08/29/basic-blocks/
http://www.friday.com/bbum/2009/08/29/blocks-tips-tricks/
http://www.mikeash.com/?page=pyblog/friday-qa-2009-08-28-intro-to-grand-central-dispatch-part-i-basics-and-dispatch-queues.html
http://www.mikeash.com/?page=pyblog/friday-qa-2009-09-04-intro-to-grand-central-dispatch-part-ii-multi-core-performance.html
http://www.mikeash.com/?page=pyblog/friday-qa-2009-09-11-intro-to-grand-central-dispatch-part-iii-dispatch-sources.html

2009/09/24:
http://www.macresearch.org/cocoa-scientists-xxxi-all-aboard-grand-central

2009/09/28:
Sleeping Barber in GCD