UPDATE: Australian details added.
The topless 911's unveiling follows the promise earlier this month of an all-new model - and months of spy photos offering a good idea of what was to come.
As with the Coupe version revealed earlier this year, the new 911 Cabriolet is built on an aluminium and steel platform.
The new folding soft-top does away with the previous model's multi-layered fabric design, replaced with composite materials and a new magnesium frame.
In base form, the 911 Cabriolet Carrera is powered by Porsche's 3.4 litre direct-injected flat-six engine, producing 261kW and 380Nm of torque.
Porsche says the regular Cabriolet Carrera will punch through to 100km/h in 4.6 seconds, with a top speed of 285km/h.
If you've got the extra dollars, the 911 Cabriolet Carrera S and its 298kW 3.8 litre engine will reduce the 0-100km/h run to 4.3 seconds, boosting top speed to 301km/h.
Both variants will be offered with either a seven-speed PDK dual-clutch automatic transmission, or the new seven-speed manual transmission teased in earlier announcements.
The 911 Cabriolet will go on sale in Australia from April 2012, priced from $255,100 for the Cabriolet Carrera and $288,300 for the Cabriolet Carrera S.