I don't know how Dell or other companies work but when I talked to Amazon rep. She said that whoever pre-ordered 1st will get it 1st. And also chat with Dell rep. Apparently the N900 is out of stock and they're expecting the next shipment to be around 45 days and that is on or before FEBRUARY 2010 . Here's a part of conversation between me and him.

1:50:16 PM Agent E&A_R
In line with extending our service, please feel free to provide your phone number so that we can call you just in case we got disconnected due to unavoidable server to computer link connection issues.
1:50:17 PM Customer Ken
very good how about u
1:50:56 PM Agent E&A_R
I'm doing fine, thanks for asking =)
1:50:59 PM Customer Ken
i just have a quick question about the nokia n900 , do you guys have it instock? and that if i placed an order right now, when do i expect the shipment
1:52:54 PM Agent E&A_R
I'll be glad to assist you on that. May I have the Dell part number of the item which can be located below or just at the right side of the item in Dell.com ? For me to accurately check on its specifications and details
1:53:24 PM Customer Ken
Dell Part# : A3076016
1:55:24 PM Agent E&A_R
thank you
1:55:24 PM Agent E&A_R
give me one moment please
1:55:35 PM Customer Ken
ok
1:57:04 PM Agent E&A_R
thank you for waiting
1:57:09 PM Agent E&A_R
We are out of stock for it
1:57:19 PM Agent E&A_R
and I see we have a 45 days lead time for it
1:57:32 PM Agent E&A_R
so most probably , the estimated delivery date is on or before 02/2010
1:57:45 PM Customer Ken
so you meant that about 45 days for the next shipment?
1:58:11 PM Customer Ken
february of 2010?
1:58:29 PM Agent E&A_R
Yes that is correct
1:58:44 PM Customer Ken
okay, thanks