I read a good article over @ overclockers, discussing why turbulent flow is important...
I'm sure many of you are aware of it, but if not check out @ watercooling section, the name of the article is:
"Watercooling Physics - Laminar and Turbulent Flow"
http://www.overclockers.com/
I think, only OC-watercool's swirl designed blocks and Dtekcustoms upcoming TC-4 are based on this approach...