However, most people at the Boston store weren't drawn by the new operating system, but rather by the opportunity to get free tickets to meet Boston Bruins hockey player Patrice Bergeron there later in the day. Still, among the 30 people in line, there were still a few Microsoft diehards.
See a video from the Boston launch.
Ashley Kwon arrived around 6 a.m. and was the second person in line.
"I actually got up at 2 a.m. to update three of my machines," he said.
During his wait, he won an Xbox One as part of a raffle. He said he already has one of the consoles, but would use the new one in another room.
He said he is most looking forward to Continuum, the feature that allows the OS to adapt depending on which device it is being used.
At 5 a.m. Louis Ciano, III got in line.
"Everyone is interested in the 'staht' menu," he said with the traditional dropped-R Boston accent.
Ciano was one of five million who were part of the Windows Insider Program. He had been testing the operating system and providing feedback to Microsoft.
Many of the Bruins fans who were in line didn't stay at the store after getting their tickets. After 30 minutes only about a dozen people remained inside.
In San Francisco, Microsoft Store Manager Greg Ginther said that people have been coming in over the past several weeks asking about Windows 10. Prior to Wednesday's launch, store employees could let people try out a preview build of the operating system and show them how to reserve a free upgrade for devices running Windows 7 or Windows 8.1.
Now that the operating system is out, people can actually have store staff install the upgrade for them, if they don't want to worry about managing the update themselves.
"So, quite a few folks are really excited about being able to just drop off [their device], have us work on it for a while and grab it from us once it's complete," Ginther said.
Starting on launch day, Microsoft stores will be hosting workshops for people who want to learn more about the operating system, in addition to helping them get set up.
Nick Barber covers general technology news in both text and video for IDG News Service. E-mail him at Nick_Barber@idg.com and follow him on Twitter at @nickjb.