And I don't.
But... today the BBC officially announced news. So if knowing who new cast members are too much spoiler for you -- read no more!!!
Myself, I don't actually feel knowing actors count as spoilers. I have a fairly broad interpretation, though, and I've read ACD. If you haven't read any of the original stories -- and you've managed to avoid tumblr, or maybe you've blocked Google from showing "BBC Sherlock" to you -- then again, you may not want to know any more.
Final warning: What I will do is not write out speculation or titles, if they're spoilery... if you want to know, click the links. If you don't, you're safe.
SPOILERS below the cut.