I'm pretty sure there are lots of Earth-like planets in this universe. There are of course many details that all have to be taken into account when determining if a planet could be suitable for life in the form we know it, but considering that our galaxy has got 300 billion stars and the observable universe (which is just a part of the whole universe) contain over 100 billion galaxies, I'd say the chance there's no other star that has got even one earth-like planet is close to zero.
As far as any other earth-like planet being inhabited by some kind of life form, it's a bit harder to calculate the probability. We know about one earth-like planet (the Earth), and that one contains life, so that would make the probability of an earth-like planet containing life 100%. Then again if it didn't, we wouldn't know about it because we wouldn't exist, so that calculation goes out of the window... But if I'm going to make a wild guess I say I definitely think there is life on other planets.
Are there intelligent life forms on those planets? The Earth has had several mass extinction events where most of the world's species died out, and there's no evidence that any of the earlier geological eras produced any intelligent species before they were wiped out. I would assume that even if there are lots of inhabited planets in the universe, the vast majority of them would only contain micro organisms at any given time. Then again, I think it would be weird to assume that the number of planets with intelligent life would be exactly one. So my guess is a large number of inhabited planets, of which only a very small percentage has intelligent life forms.
Do I think any humans will ever meet an alien life form? Definitely not. Even if it would be physically possible with the right technology for fragile intelligent life forms to travel the type of distances that we are talking about (which of course nobody has a clue about at this point, but which i seriously doubt), I can't see how any given life form would have time to figure that out and then actually do it before it goes extinct.
I also think it's difficult for anyone to appreciate the distances we are dealing with here, since they are so far beyond the capability of our imagination. This website is pretty interesting although it didn't do much more for me than help me realize that my brain can't imagine sizes and distances that aren't extremely close to my own size: http://scaleofuniverse.com/