The anonymous poster of the first comment is an interesting, if not platonic example of a conspiracy theorist. How can you hush up what is in plain sight? Does he think amateur telescopes (even the ones you build yourself) all come with a non-disclosure agreement about anything concerning Mars? Though the detail you can record using webcams is of course limited, no "canal" or other structures are visible, despite claims to by many astronomers in the past (mistranslation of Italian canali = channels lead to this hype). Spacecraft from the USSR (phobos) as well as the USA (mariners, viking, ..) gave the same results: it is a dry, dusty and cold place. Given the bitter differences between the two regimes at that times, it is unlikely they would ever conspire together.
There may be life on Mars, but if so, it will most likely be microscopic (Viking landers tried to find it, but only got inconclusive results). I am (as a scientist (oops part of the conspiracy)) always excited, but also a sceptical about spectacular new findings. Spectacular claims require spectacular proof, to paraphrase Arthur C. Clarke. However, should there be proof positive of life on Mars (or Europa, one of the Galilean moons of Jupiter), it would be the discovery of the century, and I would be over the moon. When standing in my back garden with a telescope, and seeing several galaxies in a single field of view, each consisting of billions of stars, I cannot help wonder whether someone is looking back, and maybe wondering the same.
Why are they not paying us a visit? Its the English game of cricket, as any Dougals Adams fan knows.