I don't share the excitement. First contact with an alien civilization arriving in outlandish craft and possessing unprecedented technology? It's been done -- Cortez and Lewis & Clark were greeted with open arms. And we know how that turned out for the greeters...

Hmmmm, maybe they should be afraid of us, considering the track record, but your point is well made. That which we have wrought could be wrought upon us.

Hard proof of other sentient beings would truly be a thunder clap across human awareness; arguably a real defining moment from which nothing is ever the same again. I would like to live to see it, but I think 20 years is wildly optimistic. I might not like to live to really see aliens on earth (for the reason listed above), but I'd really like to see how the masses would react to proof that homo sapiens sapiens isn't the only big brain west of the milky way.

At any rate, just picking up an ordered radio transmission wouldn't be considered "communing" with other beings at least by me. Our luck the first transcript will work out to be like some alien martha stewart explaining to its enthralled alien listeners how to make a scrumptious wombat soup.