I know they do, but I prefer to go by real numbers.
Another example: Duke Nukem is listed as Aug 3rd, but was actually available Aug 10th. I have tones more examples really.
As for FB 3.0, search for it and refresh several times...the screenshots are being updated as I write this.
Edit: 9to5mac also reporting this:
http://www.9to5mac.com/Facebook-3-iPhone