This apparently _does_ take that long, but should absolutely not.
If that's the case, then either Microsoft forgot about them, or they carefully orchestrated a PR scandal against Google (wouldn't be the first time - like the time they built an unauthorized Youtube app that Google specifically told them not to build, and then notified the whole media about it, putting words in the reporters' mouths).
What I find interesting is that there are at least a couple of cases in which bugs were marked as being subject to the 90-day disclosure deadline, but not made publicly visible until days or weeks after the deadline had passed.
https://code.google.com/p/google-security-research/issues/de...
https://code.google.com/p/google-security-research/issues/de...