By the time they started letting people in, there were close to 20 in line. By the time I left with my phone it was closer to 30-35 people inside the store.
They had a guy come out and say they had plenty for everyone (so at least 20) but I couldn't get any specifics on how many even when I was checking out. I did see the employee helping me open up a box that contained 8 or 10, but I have no clue how many of those boxes they had. 2 people in front of me ended up not being there to buy phones, just went to accompany their friends. They had 6 registers open so I was the last person to be first at a register. I was out of the store by 9:10 and I was done at the same time as the first 5 who had been there for a while.
When I left though, it was 5-6 people per line at each of the registers (30-35 total). If you don't want to be in that store forever, then get there early.
I ended up there about 30 minutes early as I had a final at 8am and finished in a little over an hour and the store is about 10 minutes from where I go to school. I think I was the first one there, but I waited in my car until I saw another person get in line. Ended up being three of us total and we just chatted for a bit until they opened up! Had no issues at all exchanging for the Nexus! Completely forgot they were even releasing a white razr today and they didn't even try to mention it!