It's always interesting to speculate what the longer lead times means.
The PowerBook has been on the long lead time for BTO the longest, so unless its a critical parts issue, it will be updated this week probably. The PowerMacs could be parts, but I doubt it as any part change bumps the leadtime up - unless Apple has a lot of orders for standard config PowerMacs.
In truth, there are several other threads which have cmmented about the leadtimes and it's all speculation.
There will be some number of product lines updated soon by Apple.
Those who just bought machines and already have them, it's the luck of the draw, don't whine so much. Or stop buying new machines as another new model is always around the corner.