This is the first thread on this subject. Ah, the good old days.
This thread probably has the most info, but it got ugly and we had to close it. (Edit - After re-reading this monstrosity, I noticed that most of what Justin posted in his long post there on page one had very VERY little to do with discussing digital cable specifics. Instead, it goes off on a tangent of analog wire [which everybody agrees effects audio signals noticably] and CD frequencies and word sizes. -Taxi)
Wash.
Rinse.
Repeat.
There are other threads in the forum about this. (A lot.) But these are the main ones.