If you were on tumblr, or Twitter -- and probably elsewhere -- you may have heard the August rumor around 1-March-13.
I.e., someone was spreading it around the 'Net that Sherlock season 3 was being aired in August 2013. This is not true.
I get the impression that it may have been someone mistaking their months and doing an April Fool's, but it may have been that August: Osage County comes out in August. And which Benedict is in.
Luckily, someone (or several someones) asked Sue Vertue. She said Not August sorry...
Wherever you are, whatever media you use, if someone brings up Sherlock and this August, do please squelch it!