Supreme Court docket - Dog sniffing

The title of this one makes it sound like a joke, but it would not have reached the Supreme Court if it weren't important.  It is really about what makes a search by authorities (police, homeland security) reasonable (or unreasonable) according to the 4th Amendment.  

The Founding Fathers were against search without probable cause.  The justification is a great example of our strong belief in the value of liberty.  Without the 4th Amendment, the authorities could harass someone either because they thought they might have done something but really have no clue or just to be annoying to someone they don't like.  The searches could be disruptive to the person's life, embarrassing (the search could discover something not illegal but that the person would rather keep quiet, such as an addiction to lolcats) or uncover something that is illegal but that the authorities didn't know about previously and just got lucky.  

So - on to dog sniffing.  When people search, they can see the embarrassing or illegal items along the way.  But dogs are trained to signal when they smell one specific thing.  Drugs.  Cash.  Produce (at the border being brought in illegally through Customs).  So if the police have the right to search only for drugs, using dogs ensures that they won't identify anything else.  The dog can stop at the door (or not open the suitcase).  So in theory, using a dog eliminates the unreasonableness of a search that would be intrusive if it were done by a person.

So if the police don't have a warrant to search a house for drugs, they can bring a dog that is trained only to signal the presence of drugs to the front door.  If the dog smells drugs, that would be probable cause for a warrant to enter.  If not, nothing else is discovered and there is no harassment or inconvenience to the resident.

So is this a good balancing act for liberty and safety?  The Supreme Court will let us know this term.