ET, Phone Home...Collect.

The Hubble space telescope's recent outstanding images from space made me muse about what may actually be "out there". Given there're at least a billion stars in our galaxy and at least a billion galaxies, the odds are simply too large for extraterrestrial life NOT to exist.
What would constitute 'First Contact' with an ET life form? Any such claim of 'contact' would of course need compelling scientific proof - we humans demand that - but what is ENOUGH proof? We already have astronauts claiming cover-ups, skeptics saying UFOs are weather balloons, past civilisations, “Chariots of the Gods”, lost technologies, seemingly impossible logistics of long-distance space travel, laws of (human) science saying nothing can travel faster than light...
And what's meant by “intelligent species”? Does that mean “sentient”? Does it mean “as intelligent as us”? Oh, such human arrogance: to think we're the only sentient beings in the universe, or the yardstick to compare ET intelligence against!
For years now we've been beaming radio waves into space. But surely ET technology is more advanced than ours, ie: not wave-based? Perhaps some kind of particle-based communication system?
We can only imagine the huge impact of the future discovery of ET life! Until then, we wait and keep watching the stars through Hubble. But remember: those bright sparkles died eons ago and their light is only reaching us now...so what does THAT tell us? That we're waiting for ET to phone us...?