I like this article, but the title is deceiving.
I read it expecting to find project milestones that hint to it's readiness to take off. I think a more appropriate title would be "How To Know You Are Ready To Make Your Side Project A Startup"
All in all thanks for your advice.
how to know your side project is ready to be a startup:
* you have employees
* you have investors
edit: note that this is a tongue-in-cheek response to the article that implies that you might somehow be considering something a "side project" when having employees and investors to answer to.
According to the Facebook Effect by David Kirkpatrick, for most of the first 6 months of Facebook, while the site was been growing at Harvard and during the first summer in California, the Facebook crew still did think of Facebook as just a project or maybe a fad, which is one of the reasons they spent so much time on Wirehog, a short lived peer-to-peer file sharing program. However, supposedly shortly after the first investment from Thiel that fall and with a lot of pushing from Sean Parker, Zuckerberg and his crew did lay out the entire multi-year plan for Facebook including photo albums, the news feed, the platform, and Connect.
The content vs. title of the article makes me wonder if a side-project vs. the start-up is more a matter of your mentality toward what you're doing and the stage you're at than the project itself.
If you are thinking too small, it is up to you to figure out the bigger opportunity. Doesn't the rest flow from there?