[breily]

Why not? It seems like if we can see them they could see us - unless you just mean our planets are smaller so they'd need a better telescope than we can make?

[gommm]

Because we do not have any planets as huge as Formalhaut a, b and c in our solar system...

[13ren]

Yes, and those planets are also hotter, therefore brighter and more visible.

The sky might be full of earth-like planets, and we wouldn't know (yet).

unless... detecting star-wobble is already sensitive enough to detect earth-like mass and distance from sun?