As the Backflip will mark the first time U.S. customers under contract with AT&T will have the option to choose between Android and the iPhone, every Motorola Backflip that AT&T sells might potentially be at the expense of an iPhone.
That Backflip sold will not generate Google any ad revenue since it will offer Yahoo/Microsoft search exclusively. Nor will the Backflip generate any license revenue for Google, because Android is licensed without a fee.
If that buyer would instead have bought an iPhone, the search from mobile Safari would have some non-zero value.
It is therefore pretty obvious that, at least in this instance, Android is destroying value for Google.