Some of you seem to be confused about search warrants, court orders, constitutional rights, and similar US laws.
Search warrant: "A search warrant is a court order issued by a magistrate, judge or Supreme Court official that authorizes law enforcement officers to conduct a search of a person, location, or vehicle for evidence of a crime and to confiscate evidence if it is found. A search warrant cannot be issued in aid of civil process.
Search warrants are not issues to private companies or individuals. They are for law enforcement. A search warrant doesn't apply in this case any more than I would need a search warrant to take pictures of my own house if I was collecting evidence for a vandalism/theft case that I reported.
Court order: "A court order is an official proclamation by a judge (or panel of judges) that ... requires the carrying out of certain steps by one or more parties to a case."
If MS had asked for a court order to gather evidence from their own servers for a criminal case in which they are the victim the judge would no doubt think they were total idiots. Court orders are used to force someone to turn over information/evidence that they are otherwise unwilling to turn over.
As far as "rights to privacy" with services offered by a private company, that does not apply when you are involved in a crime. The terms of service of any service provider clearly state that the data on their system can be searched/seized/deleted/etc. if there is reason to believe you are doing something illegal (which these people were). Microsoft didn't go trolling through all of the data in Hotmail to track down the blogger. The blogger emailed Microsoft to ask them about the stolen information! That's a lot like the stupid criminals that accidently drop their wallet at the scene of the crime. Do you think a search warrant is needed for the victim (or law enforcement) to look inside that wallet?
Some of you act like this is a case were someone said something bad about MS and MS abused its power to hunt them down and destroy them. This was an investigation into a major crime. The reality is that the two people involved in this crime were incredibly stupid. The former employee was committing several crimes and he used MS services (SkyDrive) in the process. The blogger emailed Microsoft using his Hotmail account to ask them if the stolen authorization codes were legit. How stupid can you get?! If someone stole my phone and then started using it to call their friends and take pictures, do you think I should ask for a search warrant or court order before I look at their calls records on my cell phone bill? Should I get permission to copy their selfies that automatically upload to my OneDrive? What do you think the police would say when I ask them for permission to log into my AT&T account and read the text message that the criminal is sending? I'm pretty sure they would say, "why are you asking us for permission?"