Again, the point I was making (with 10 years of professional SEO experience under my belt) was that for some companies, search isn't how their products are found... If that's the case, an early focus on SEO (the time consuming part-- not the "low hanging fruit") is distracting from more effective distribution channels.
The degree to which you focus on SEO should be proportional to how much your customers are searching for what you offer (you should also roll into the equation the KEI/competitiveness of the target keywords).
There are plenty of businesses whose target customers do NOT USE GOOGLE as a tool find the product. 37Signals is a great mom-and-pop example. Building the next great search engine is another example (people wouldn't search for "search engine"). There are countless others. In addition, any business that's diving into mature verticals where Google is claiming the "2nd click" (weather, images, etc) ought to seriously consider eschewing SEO as an early strategy in favor of other distribution efforts.
I insist, even if you have a viral web app/widget, to not focus on SEO from day 1 is missing the whole point of the net and will cost you bucket loads in the long run at best.
FWIW I would be very interested to hear of the app / widget that you are enjoying the 8% weekly growth. Mine is myplaylist which is also enjoying high viral growth.