Via Mark Jen:
"...noticed that jeremy and others had posted about the launch of Yahoo Search Developer Network (YSDN). note the striking resemblance in name to MSDN - i'm sure that isn't a coincidence. yahoo is really taking the lead here by not just providing web apis (which google has had for a while now), but in really creating a developer community. a good chunk of YSDN is focused on getting the word out about user developed apps, connecting people together through mailing lists and having people share expertise through a community wiki.
it seems that yahoo is clearly imitating microsoft in creating an ecosystem for developers; aside from fueling the creation of new and innovative user experiences, the emergence of a developer community enhances platform stickiness."