Denver was a hive of software startup activity back in 90s. I flew in there to look at a company in 1992 o behalf of my employer (Geac at that time, based in Markham, Ontario, I was based at a subsdiary FACT in New Zealand). My lasting impression however was Freddy Fudpuckers. Hilarious name and hilarious food. Anyway I digress .... for those just out of kindergarten you would be excused for thinking startups are a new idea. For those of us with decades of creating new bugs, we have seen the locations for startups move around depending on tax policy, cost of living, and being close to a major innovator (Austin Tx = IBM and NASA as an example).
I think you're right. The source for the story, on arcgis.com, seems to have updated maps that don't show the odd circle, and Colorado displays with a bigger circle right on Denver. I think for some reason Denver was rendered at (0,0) within Colorado's boundaries in the screen shot Qwartz used.
I remember flying into Denver's airport a year or two after it opened and thinking "Wow, this place is in the middle of nowhere." I visited again a year ago and was surprised to find it quite built up, and located close to the places I wanted to go.
--edit: I just saw alanh's sibling comment. They moved Denver!