Successful software development

What does it take to make a successful software development project?
Consider Google AdSense: it went into full-scale production in 2003.
Now it's 2008. Microsoft still didn't implement its version of AdSense competitor. Yahoo implemented something, but that something is not for everyone and is available only as a very limited beta-version.

5 years passed, since AdSense production launch. But nobody can reproduce what Google did in probably less than couple of years. Not even such high profile software development companies as Microsoft and Yahoo.

What do you think defines component of successful software project? Good developers? Good team leads? Good top management?

I think Good team leaders with proper backing from strong top management team is the key.
Team leader and top manager could be the same person. That was the case when Google just started with their now famous search engine in ~1995-1997. Serge Brin and Larry Page were software developers, team leads and top management at the same time.