I'd have to vote no, myself.
Considering how many possible little rocks that could support life are out there, even if you low-ball the figures - I find it hard to believe in a Universe this vast, we and the other inhabitants of this planet are the only living things out there.
I suppose you have to define what exactly Life IS - but even assuming we're narrowing it down to something biological made up of cooperative cells created by a mixture of chemicals & molecules - sentient or not, I think there must be other forms of life out there.
After all we've already learned about how tenacious life can be - extremophiles thriving in tempratures, pressures and in chemical environments we never before assumed possible, I think that opened the door considerably for reason that there could very well be things alive on worlds far beyond.
Seems given a proper environment for molecules to intermingle freely (such as in our own primordial ocean) extensively more complex groupings and chains will evolve - chemical reactions lead to further changes, and with the addition of energy sources such as lightning, or solar radiation - take a few million or billion years, and don't be surprised if something eventually crawls up out of the ooze.
The sad part is that we'll probably never have an opportunity to discover and meet other forms of life in the Universe, save what might be residing in our own solar system - the distances and hazards of space travel are mind-boggling...
Unless someone invents that Tachyon-drive, I guess we're stuck here on our own spinning little blue ball. But I guess that's reason enough to take care of it - not much to fall back on if we screw this up.
-2 cents-
