Well, first off, I think that t-shirt in the accompanying photo is awesome!  I think a startup is kinda like pornography was for Justice Potter Steward - I know it when I see it.  One guy sitting around blogging, even if it gains traction and succeeds as a revenue generating activity, is not a start-up, it is getting lucky.  One guy with a business model, a revenue model and a plan for future growth, where the purpose of the activity is specifically to generate income, well, that could be a startup in my book, even if it is also based on blogging.  To me it is a question of intent.  If there is an intention and a developed business plan to make money, it is a start-up.  If it is doing something you like, and you hope you make money from it too, not so much.