My sup is a bit crazy over keeping all research private - she even gets me to hold back on conferences, and leave the 'juicy' bits for publication. She's been burned in the past though, so I imagine that's why. It has taught me to be really cautious about telling anyone what I'm doing specifically - I've even had one girl trying to copy some of my research which is a bit scary.
Anyway, can you make the blog private (I have no idea on technology!) or how about using microsoft one note?