I, too, ordered a BTO 15" PB (1.5 with SD/100GB HD) - on August 1st, and was quoted shipping "on or before August 5th". It's been "sent to manufacturing" for the past three days, but no other updates. I just got an email saying my order ran into "an unexpected delay" and that my new ship by date is August 11th.
I originally ordered a refurb 15" 1.67 but wasn't happy with the 7-10 business day time to ship, and realized I needed the extra disk space more than the fastest processor, so changed my order. At that time, the stock shipping was same business day on all the Powerbooks, so I thought that it'd be a good chance I'd get my BTO unit fast - and Apple quoted 1-3 business days to me for shipping.
My gut says updates on the 9th, but it may turn out just to be component shortages. Here's what the USA Apple Store has for shipping as of Saturday 6:45 am PDT:
Stock Shipping @ Apple Store:
12" Combo - Same business day
12" SD - 1-2 business days
15" 1.5 Combo - 1-2 business days
15" 1.67 SD - 2-4 business days
17" - Same business day
BTO Shipping @ Apple Store:
12" Combo - 1-3 business days
12" SD - 1-3 business days
15" 1.5 Combo - 1-3 business days
15" 1.67 SD - 5-7 business days
17" - 4-6 business days
What do you think?

Anybody have more insight into this delay?? I don't mind the wait if that means an updated system for me. However, I'll be happy with the unit that I ordered. I doubt it's gonna be anything big. If it were, the iBooks would have been bumped to the level of the PB's.