These days, the announcement of a new extrasolar planet is not that exciting. We've got your jovians, your superjovians, your "hot Jupiters", your iceballs ... but some of these planets are a heck of a long way off, and none of them have been even remotely habitable (gas giants twelve times the size of Jupiter with temperatures of 900K? Not much of a vacation destination).
As james_nicoll reported last night, a more-or-less Earthlike planet of about five Earth masses has been detected in the habitable zone surrounding the red dwarf Gliese 581, 20.4 light years away in the direction of the constellation Libra. The planet's exact composition is unknown; if it formed in situ, it is likely to be a very Earthlike iron/silicate rocky world, but it is also possible that if it formed beyond the snowline and migrated in, it may be a water-world with a hugely deep world-spanning ocean (possibly possessing more than an Earth mass of water). In short, it is "not beyond the bounds of possibility" that it could be a habitable world.
Earth-evolved vegetation wouldn't do well under a red dwarf sun. However, the size and mass of Gliese 581 c suggest a surface gravity of around 1.6G (heavy, but manageable), and 20 light years puts it within reach of an automated probe if we can figure out a way to get one up to an appreciable fraction of lightspeed. If we can somehow get a ship up to relativistic speeds, it's within reach of a manned expedition.
(Those are big if's, of course.)
The linked article lists six possible orbital fits for the Gliese 581 system with both currently-known planets (the five-Earth-mass 581 c in its 12.9-day orbit, and a previously-detected Neptune-size planet, designated Gliese 581 b, in a 5.366-day orbit.) I can't help wonder what it's like when the two planets pass by each other.