We didn't actually count them, but the local Barnes & Noble store in Reston, VA last night had at least a hundred (and possibly twice that many) people in it at about quarter after midnight when we stopped by to see how it was going.
As would be expected, there were a core group of fanatics who were wearing hats or robes reminiscent of the popular Harry Potter book series, but most of the folks were just normal-looking people standing in large, mostly orderly groups waiting for their number to be called.
The folks at Barnes & Noble, to their credit, appear to have settled on a pretty good scheme, whereby they let everybody in to the store and then called them up to the front by numbers (twenty-five at a time) so as to avoid the mad rush and pushing that usually occurs in long lines.
From a marketing perspective, this had the added bonus effect of providing the customers with an opportunity to browse for other books that they might like to purchase simultaneously.
We didn't purchase, but it was an amusing spectacle. My copy is expected this afternoon.