I just spoke with a representative of Nokia Shop (shop.nokia.co.uk) asking about when to expect delivery of a preordered item.

I didn't mention N900 or give my order number - he asked straight away "is that for an N900?" :-D

Anyway, he said all the preorders are being shipped today and Monday, and that I'll get an email when it is shipped.

As I have ordered express delivery, it should take "1 working day", whatever that means in practice.

Needless to say, I haven't received an email yet. But then, I was rather late in the queue, ordering only 1 month ago :-)