Do you need a technical co-founder?
jeffreytalajic.com
jeffreytalajic.com
Longer answer: Acquire technical skills.
There, I've saved you the effort of reading the article. Move on ...
(Wow - I'm grumpy today ...)
I guess it depends on the domain of your startup, but I generally disagree with this. Maybe it's because I'm focused on B2B scenarios, but - as a hardcore techie type - I absolutely see the need for a "business guy" to partner with. Marketing, sales, business development, fund raising, PR, etc.... all of those things are things that are NOT my strengths and would be better done by (or at least in collaboration with) somebody who specializes in those things.
Regarding sales in particular... maybe it doesn't matter so much if your startup is a webapp that either goes viral or doesn't, but if you're selling a product (or service) that requires face to face selling, I expect you'd be hard pressed to overestimate the value of somebody who's good at the selling side of things.
Hell, I'm actively seeking a non-technical co-founder, especially one of those "can sell ice to eskimos" or "can sell Bibles to the Devil" types. I may even go find a good used car salesman and see if I can get him/her up to speed on enterprise software. :-)
And when you think of technical founders like the Google guys, Bill Gates, etc, they started as technical and acquired the business skills as things developed. So yes, business skills are super important. But they can be acquired.
I'm not so sure that a business guy will just learn some technical skills in the early days of a startup. So the tech guy can learn business, but the business guy can't learn tech.
That said, I think there could be a role for "business guy" even earlier in the process, depending on the details. If you're "scratching your own itch" and you know what you're going to build, then that's one thing. But if you're doing the "find a problem somebody has, and solve it" approach, then you could start the Customer Development process from day 0, and a guy/gal with experience in marketing / product management / etc. could be valuable then. Especially if he/she has some domain knowledge in the field you're working in.
I'm not so sure that a business guy will just learn some technical skills in the early days of a startup. So the tech guy can learn business, but the business guy can't learn tech.
I think it just depends on the individual. And when I say "business guy" I mean "business guy with some technical knowledge, particularly relevant domain knowledge." Which is one reason that finding the right person has been a challenge. I joke about finding a "used car salesman" and teaching them about software, but realistically, I'd like to find somebody who has experience selling enterprise software already.