Actually, what is far more important than size is location. Any solid-surface planet that is located in the so-called "Goldilocks zone" where liquid water can exist is a possible (likely) candidate for harboring life.
What's the furthest distance a typical planet based radio wave can travel before being attenuated too much or just swamped by static and other signals?
This is exciting news though - I for one absolutely do not think we are the only intelligent life in the universe.
We can't just be a one off although for our sake I hope whoever we encounter are more intelligent and friendly than we are likely to be if we ever encounter a less developed race.