There's a great deal of information about extrasolar planets floating around the web. Some of the best stuff can be found either at NASA's website or linked from there.
It's certainly true that extrasolar planets are very common -- this is a big paradigm-shift from just 7 years ago, when a small group of astronomers observed a distant star and saw a "wobble" with a truly bizarre period: 365.25 days! Turns out they got their math wrong (they measured the period of Earth's revolution!), but shortly after that, astronomers did start finding real instances, though the smallest to date has been about 4 times the mass of Jupiter or so.
Clearly, this implies that planetary systems are more commonplace than previously believed, although no real guess as to the proportion of gas giants to terrestrial planets can be made.
The article had a bit of sensationalism attached to it that I wish hadn't been. Though Jupiter has definitely been a helpful factor in protecting Earth from past impacts, it certainly isn't the great protector that the article implies. For completeness, Earth's moon should be considered for its ability to protect, as well, even if to a lesser degree.
As is common with these kinds of articles, the journalist knows just enough about the facts to get things wrong. Comet Shoemaker-Levy should be Shoemaker-Levy 9 (this may sound like I'm picking nits, but the Shoemakers and David Levy have codiscovered a sizeable number of comets), and the implication in the article is that Jupiter saved us from certain doom at the "hands" of that comet, even though, in fact, the comet would never have crossed Earth's orbit.
While I expect that someday we will discover extrasolar terrestrial planets, I would be loathe to make anything more than a hopeful statement. I certainly wouldn't indicate that there are probably as many Earth-like planets as Jupiter-like planets: 80 data points does not a small error-bar make!
I also am wary of the journal "Astrobiology." Coming from the scientific field, and knowing that most important abstracts are published either at conferences or to the journal "Nature," I am inherently skeptical. Of course, again, I'm hearing the scientists' words through a poor interpreter, and won't condemn someone for something they might not have said.
Bottom line: I think we'll discover a plethora of planets, both Earth-like and Jupiter-like. As technology improves, I think we'll se subtler and subtler motions of stars. I also think we'll decipher more complex motions (with our current technology, if we were on a planet orbiting a star 40 Light-Years away, we would have trouble even detecting Jupiter, let alone the other 8 planets) as tech improves. Eventually, we'll discover terrestrial planets, and then use knowledge from other areas of astronomy to determine the presence of methane in the atmospheres (surely aliens fart, right?!) of these planets, and hence, life.
Someday, we might even discover life elsewhere. I'm holding out for Europa to house life, though I'll only believe it when it's confirmed.
I certainly love the press that astronomy gets from time to time. I just wish I wouldn't have to spend all my time in planetarium shows (my career is working in a planetarium) correcting good-intentioned-but-wrong statements by overeager journalists
It's starting, but not quite complete. If the moon can support some bacteria, certainly many other places can as well. Maybe a minority, but a signifigant one....
