Here's a bit of information that came from the official site for Blu-Ray. To date over 1 million PS3 units have been preordered already. This number came up while discussing Blu-Ray and HD-DVD coverage at Internationale Funkausstellung (IFA) 2006. Its the world's largest electronics and IT show, which was held from September 1-6, 2006 in Berlin, Germany.
The site also covered other brands that have Blu-Ray so it's unclear if that number included those or if the preorder number was North America-only or worldwide. The big question is can Sony meet the demand? We'll see.