This morning a client was panicked that we have been banned by Google because Google analytics was showing zero data for yesterday. A quick check on a few other accounts and everything was clear: a pretty nasty bug is causing this. From what people on twitter are saying it has been going for the past 10 hours.
No official reaction yet from Google Analytics blog but expect one soon. My estimate is that is just a reporting error and all the data should appear soon.
Summarizing, google analytics reports missing is just a display bug.