[Schatze]

They're already discovering exosolar planets via occlusion, the problem is that the instruments aren't sensitive enough to detect earth sized planets. So yeah, not disagreeing just being a pedant.

The problem is this method won't work on solar systems where the ecliptic is not lined up in a direction where the planets will occlude the star, which will mean that the use of such a method is useless for most stars. Fortunately, we have an abundance of stars to observe. This is of course assuming that the standard theories on solar system formation hold true and that other solar systems have something roughly equivalent to the ecliptic.

As for nasa; what they need to do is find planet X. Not the bullshit conspiracy theory one, but the one that exists or has existed, based upon current models, that explains the kuiper cliff. The drop off in density of observed kuiper objects versus models indicates there is a fairly massive celestial object orbiting at the fringes of the kuiper belt.

edit: adaptive optics as I understand it would not be of use in imaging exoplanets crossing in front of a star; rather, the mechanical components of the optic system are adjusted to compensate for atmospheric distortion, using a laser as a calibrator. I'd think it'd be more masking and filtering advances that would allow imaging of exoplanets as they transit across their parent star that is the important part.