That’s the strategy if you want to make money off the use of the APIs and you want to own the services. Google doesn’t look at in the same way. I pushed Chris DiBona on Google’s take on APIs and he said, “we just want so many developers using straightforward HTTP and XML that it’s impossible for someone to introduce anything proprietary that would weaken Google“. Google doesn’t need the proprietary ownership of the services, they make their money when people use the Internet. The biggest threat to Google isn’t that someone else will implement the same Calendar API as Google, it’s that someone will make web pages uncrawlable through proprietary extensions to HTML or HTTP. They need web standards so firmly entrenched in common use that nobody can break the Internet from under them, and this pits them against proprietary evilness.
Note what Nat says in the about article – google’s biggest threat or biggest advantage is ‘open source’. They have to be at the cutting edge technology and lead development to keep their advantage. I think this is where Google beats Yahoo and MSN as they are dependent on open source stuff! And as they are are dependent – it keeps them on the edge i.e ahead of the competition. Basically success comes as long as the adrelin is kicking 😉