If you're a technical founder, with some interest and understanding on how to create some buzz around your app and get in users - I'd say, you don't really need a business / non-technical founder early on. Though, at some stage when you start scaling up, you will need someone (could be technical or non-technical) who can help on the business side. Andrew Chen's recent post has some good points on this -

http://andrewchenblog.com/2011/02/05/stanford-cs-major-seeks...

"What do geeks really need help with? It’s very simple- there’s a class of purely business-related stuff that adds value:

selling stuff and making money getting partnerships and marketing/distribution of the product funding the company scalable marketing/monetization strategy (ad arb / viral / freemium / etc.) team recruiting, particularly of other engineers and disciplines (not other MBAs please) If you are an expert at any of the above and can show it, then there’s a lot more value. Very few business folks, particularly newly-minted MBAs (with the exception of Stanford folks) or industry-switchers can really deliver on these though, which is why they’re not bringing much to the table.

Then there’s a class of things that are much more product-oriented, and while it overlaps with the skillset of some engineers, if you have great skills in any of the following, they are clearly valuable too:

design, especially visual design UI/frontend skills – HTML/CSS/JS – even if mediocre! copywriting within the product for help text, marketing, etc user research and customer development usability testing."