It's a debate that will never go away, but the question of "apps will make a platform" was in the air a lot this past weekend (starting with Skype and then spinning out into a number of other areas). The Verge's Tom Warren has captured the spirit of the weekend into an editorial asking if quantity equals success.

A number of critics have highlighted flaws in Microsoft's mobile strategy, some pointing to the number of apps available. Robert Scoble has been the most vocal recently, arguing that Windows Phone is missing 450,000 apps, and developers aren't interested in focusing their resources on building apps for the platform... Microsoft's Windows Phone OS reminds me of the original iPhone, a break from tradition but one that requires developers and an ecosystem to really flourish.

I think that everyone can agree that nobody needs 500,000 applications on their smartphone, or can even sample even one percent of them in a reasonable time frame. But if we agree that there is a sweet spot of "key apps" for each person then the question becomes a bit more fluid. How big an application pool do you need to cover a significant percentage of user's needs?

Let's say the count twenty apps to make a smartphone so personal you'll want to keep it forever. If the application pool is only 20 apps, then it's highly improbable that this will satisfy everyone. If the pool is 60 billion applications (which means everyone on the planet codes ten applications) then it's highly probable that you'll find the twenty apps you want.

Somewhere in there is a sweet spot that balances "a big number of apps" with "getting the user the apps they want and need," but until there's some serious statistical work on human nature, applications, and need (outside of asking a thousand people what app they want on their smartphone), the simplest answer is going to be keep building the application pool and ensuring people know just how much choice there is until a psychological limit is passed - which is likely to be the 100,000 mark for Windows Phone.