Just a few days after Wired uncovered a security issue on the Apple Store, the Register titles on a big security snafu at Microsoft's Passport service, that "could compromise the information stored on all 200 million users."
In pure and totally assumed bad faith, I would say that it is a regular habit of Microsoft to copy Apple but always make it bigger.
The FTC, which demanded security improvements on the service last year, is investigating and could fine Microsoft heavily if they find that the Redmond company did not follow suit to their previous order.
Microsoft has set up a page on this issue. You should check it if you are a Passport user.
I still persist in my opinion that leaving sensitive information on a third party servers remains a bad idea so far, and the level of trust you can have in a company or its developers' security skills is the big show stopper of any centralized service that handles personal data.