Yeah, I'm not so sure Micro Black Holes could really do the kind of damage people think...
However, Vacuum Bubbles on the other hand...
http://en.wikipedia.org/wiki/Quantum_Vacuum
Vacuum refers to the energy state, not the lack of air, or that noisy thing hiding in your closet.
To put it simply, If our universe isn't at the lowest energy state like we believe it is, and is in fact a "false" vacuum, a Vacuum Bubble can literally *pop* our reality. And, in a literal instant, Earth would cease to exist.
Good new is, if it happens, we'll never know.
btw, First impacts won't be until October some time, and Full Power won't be hit until sometime in... oh... 2012.