I'm a solo founder. When I started my current company, I first developed a prototype then tried looking for a co-founder shortly after. There weren't many options within my personal network (few risk takers or people with savings to burn). I expanded my search to those I didn't know, which meant going through essentially an interview process with potential candidates, but I couldn't find a match. I even had people do reversals and pitch me their ideas.

My feeling is that this kind of co-founder matchmaking is just plain hard. First, like they say it's similar to getting married. You really need to trust the person, which is why your personal network is the best source if you can pull it off (see PG talk about college buddies). Second, many people interested in entrepreneurship probably have their own ideas already.

I think non-technical founders have the best chance at recruiting technical founders than the other way around. The technical role is more straightforward (write code for the idea that the non-technical founder came up with), and potential technical recruits may be more wealthy on average.

If you're a technical founder, I'd say recruiting a "biz" person is a lot harder. Fortunately, you can just do everything on your own anyway (not that it'll be easy though!).