Ed Felton explains why people care about the 09 number (aka the AACS secret key). Go read

The user revolt at Digg and elsewhere, over attempts to take down the now-famous “09 F9 …” number, is now all over the press. (Background: 1, 2) Many non-techies, including some reporters, wonder why users care so much about this. What is it about “09F9…” that makes people willing to defend it by making T-shirts, writing songs, or subjecting their dotcom startup to lawsuit risk?

The comments on his post are worthwhile as well.