Tech Crunch reports that the Yammer platform has grown tremendously in its first week since winning top prize at TC50. Yammer CEO David Sacks says there are now 10,000 networks and 50,000 users on the platform.

In an attempt to prove their worth to many naysayers in the blogosphere, Yammer is now launching an API that will allow third-party developers to incorporate Yammer functions into their applications. The API is the same as what was used by Yammer’s own engineers to create the iPhone, BlackBerry and Adobe AIR clients, so there should be no doubts that it will work.

It seems that many people were upset with Yammer winning TC50 this year, citing the company as “a Twitter clone,” but the way in which Yammer is using the microblogging platform and the adaptations they have made to take it inside the corporate environment are what really set it apart.

With the release of the official Yammer API, Seesmic has announced it will be building support into its Twhirl desktop app, which thousands of users are already using to access services like FriendFeed and platforms like Twitter and Identica.

We created a network on Yammer after the TC50 event and have been using it to debate story ideas and pass links around. Our three members have posted 42 messages so far.