Valve is a very intelligent company.
" http://www.aperturescience.com/glados@home/ "
I have 4 points why:
1: Hype. If they do manage to "gather enough points" a lot of people will buy the game early. Not only the people who were going to buy it anyway (me), but this campaign is going viral through the internet, Guarantying new customers, which brings me to my next point.
2: Money. not only will Valve generate capitol from the sales of Portal 2, but they also make money from the discounted indie games they're advertising and selling.
3: Customer Relations. This will not only reinforce Valve's relationship with their current costumer base, but also form new and equally as faithful customers from this incredible campaign.
4: Company Relations. Not only do both Valve /and/ indie companies create income from this collaboration, but in games like Audiosurf, there is a Portal Gun as a playable avatar, this not only increases the drive for customers to play the game, but also opens up future game possibilities between the indie companies and Valve. \
that's why I think Valve is Ingenious.