In short, Nokia has shipped 19.6 million smart phones (i.e. Symbian, Lumia, and N9) in Q4 2011. Also, Nokia reported that it has shipped "well over 1 million Lumia devices to date" (i.e. till January 26th), so I would say it's quite safe to say Nokia shipped at most 1 million Lumia phones in Q4. Then Nokia shipped 19.6 - 1 = 18.6 million Symbian phones and N9 in Q4. Then in Q3, Nokia shipped 16.8 million Symbian phones.
Back in 2010, Nokia shipped 26.5 million smart phones in Q3, and 28.3 million smart phones in Q4, resulting in an increase of 6.8%. Note that in that quarter, Nokia had only Symbian phones to ship, and it actually had a well sold model of N8, which might have been sold 4 million devices during that time. But now, there's no such well sold Symbian phones in Q4, and there are actually N9 and Lumia phones in different markets.
So, let's play safe, and assume the sales of Symbian phones increased by 5% in Q4 compared to Q3. It means, Nokia shipped 17.64 million Symbian devices in Q4, meaning, N9 has been sold 18.6 - 17.64 = 0.96 million devices!
Definitely, this is the lowest possible sales number for N9. It's up to you to figure out the highest possible sales number for N9!
UPDATED ON January 28th, 2012
OK, OK, I'm adding a simple table to show you more data! In short, it shows how many N9 were shipped in Q4 with different possible Lumia sales number and Q2Q increase of Symbian sales number.
The number in read shows you when Lumia sales exceed N9 sales. So, you know who is more demanded, right?