If you read earlier in this thread you'll see that a few of our orders went into 'Boxing' already, and quite quickly (mine was ordered, built and went to 'Boxing' in less than 1 day). My order (as well as many others) has already been in the 'Boxing' stage for several days.
However, if you read on - you'll also find that the 'Boxing' stage will take longer than what one would assume boxing and packaging would take (they aren't really taking that long to box and package your computer).
It has been said that this model is assembled/built in Asia (we see this as Build, Kitting, etc) and sent back to Dell in the US (this process is shown as 'Boxing' on our end) where they package it with accessories and drop ship it from a US hub out to the customer (using the shipping method that they chose). On our end, this is where we finally see the 'Shipped' stage.
Not sure if anyone will know for sure what Dell's procedure is, but this topic was touched on a few times in the Dell forum when people were asking why it took Dell over a week to have their systems 'Boxed'. The lead times for these models are long for a reason, but usually we get them at least a week sooner than what Dell estimates.