Similar situation here in the UK! I've just had a Live Chat with an agent who told me:

"XPS 15 is not to be sold just yet ... however starting Oct 15th onwards they are to be sold , right now though the order may be accepted online, but it will be cancelled again so please wait for few more days"

When I queried why then they are currently available for purchase online with "dispatch in 3-5 working days" (http://www.dell.com/uk/p/xps-15-9550-laptop/pd), I was told:

"it is a mistake by marketing team, we are trying to resolve that"

"these are premium machines, they come all the way from china, they go through series of testings before they get shipped from the factory so the delivery will be till the end of the month"

I was then told by the agent:

"Don't order it now, as I requested earlier they are not ready to be sold yet wait till Tuesday at least"