It took me a while to join in this conversation when it is something that really interests me because I had to really think about it.
What threw me off is that it seems like the thread - as attributed to a lot of the responses given so far - look at cloning as getting an exact replica. This is not the scientific objective or expected outcome of cloning. Cloning is merely another process of "procreation" with the added qualification that it is an exact genetic match just like an Identical Twin. The difference between an Identical Twin and a Clone is that an Identical Twin is 2 siblings of the exact same genetic signature while a Clone is 2 non-siblings with the same genetic signature (I'm referring to the somatic cell nuclear transfer cloning method - just like the sheep Dolly, or popularized by the book and movie Boys from Brazil).
But, just like Identical Twins grow up to be 2 unique individuals - even sporting unique, albeit closely similar, fingerprints - so will the clone! The only thing making clones stand out is that both donor and clone would look super closely the same much as Identical Twins would. Everything else follows the same pattern of unique gene expression (hence different fingerprints). So that, even if we go beyond dogs and go to cloning humans because we really want another President Barrack Obama, you shouldn't be surprised if you end up with an allergy-laden, asthmatic, athritic, black man who can't dribble a basketball asking customers, "Do you want fries with that?" in a Southern drawl.
So, the question is not whether we want the exact same dog (immortal dog?) - because we won't. The question is whether we find the process of cloning as an ethical alternative to breeding.
My position is not firm on this. I usually deposit ethical questions to my Christian foundation and there's nothing in it that supports cloning and at the same time, there is nothing on it that opposes it.
In a situation where we want to preserve an endangered species or we want an alternative to farming for food consumption I don't see any ethical reason not to add cloning to the list of viable alternatives. When it comes to breeding dogs for a pet, I don't know. We haven't yet solved responsible traditional breeding methods with all the terrible breeders out there, I would hate to add another aspect to breeding that can be easily mis-used.