This is an very good commentary from Joshua Zyber at High-Def Digest:

[Link: tinyurl.com]

This part I found very interesting:
"During its first week of release alone, the Standard-Def DVD edition of '300' sold 5.10 million copies. That's one single movie on DVD, during just one week of release, moving more than twice as many units as all Blu-rays and HD DVDs combined could manage in 6 months."

Both formats have a long way to go to catch Standard-Def DVD's.