It looks like the era of Dynamic languages has officially begun. Yahoo has chosen not Java or C# or C++, but PHP, the lowest common denominator for dynamic languages, as the foundation for its app dev platform.

http://developer.yahoo.com/yap/guide/
http://developer.yahoo.com/yap/homepage/

So has Facebook . . .

http://wiki.developers.facebook.com/index.php/Creating_Your_First_Application

And the top three MyspaceID software development kits (SDKs) also use dynamic languages.

http://wiki.developer.myspace.com/index.php?title=Category:MySpaceID_SDK