Vindu Goel has written at the New York TImes about why Google cancels projects. It is in part based on comments by Jeff Huber.

http://www.nytimes.com/2009/02/15/business/15ping.html?_r=2&ref=technology&pagewanted=all

● Has it found an audience? Is it popular?

● Is it growing? Is it growing fast enough?

● Will a Google employee support it?

● Does it address a big enough problem?

● Does it meet performance targets?

There are also some comments at slashdot.

http://tech.slashdot.org/article.pl?no_d2=1&sid=09/02/15/1532210