press release or the 50 page preprint for those of you that want the gory details.
The Lick-Carnegie collaboration used over 11 years of continuous radial velocity measurement of the star Gliese 581, a nearby red dwarf star with about 30% of the mass of the sun (type M3V for you astronomers out there) that is already known to have two other small planets right on the inner and outer edges of the star's habitable zone - effectively jumbo-sized versions of Venus and Mars. Gg, however is right smack dab in the middle of the habitable zone with an estimated average surface temperature of 228 K - chilly but not "lifeless chunk of ice" cold. Also helping things out is the fact that planetary evolution models indicate that Gg is probably tidally locked to its sun, meaning that one side is in eternal day and the other in eternal night. This might allow the planet to have a wide range of temperatures - from scorching hot at eternal noon to extremely cold at eternal midnight. Gg is also about 30% more massive than the earth, meaning it's gravity is probably something like 10% stronger than ours, which might be helpful in holding on to an atmosphere.
So when do we send tourists? Probably not for a very long time. Gliese 581 is about 20 light-years away and our current fastest moving spacecraft (Voyager 2) is only going about 0.001% of the speed of light, so it'll be a very long time before we get a probe there to check it out, much less a person to write a travel review. And it gets worse. Since Gg's orbit doesn't happen to line up with our line of sight its sun, we can't even use satellites like CoRoT or Kepler to watch Gg transit across its sun. It looks like more information on Gg is going to have to wait for the next generations of missions like SIM-lite or New World Explorer which should be able to directly image it.